A Study in Museum Valuation and the Mosaic Market
This report draws on auction records, primary market data, appraisal literature, and institutional policy documentation. Where auction figures are cited, they reflect published hammer prices and buyer’s premiums as reported in publicly available sale records. Where commission economics are discussed, the report draws on public art program documentation from the U.S. General Services Administration Art in Architecture program, the National Endowment for the Arts, and published accounts from practising mosaic artists.
Methodological honesty is required at the outset — and it is part of the argument. The data landscape for mosaic as a contemporary art market category is almost entirely absent, and this absence is a finding of the report, not a limitation of it. No auction house maintains a dedicated mosaic category. No appraisal organization publishes mosaic-specific valuation standards. No arts funding body tracks commissioning fees by medium at the granularity needed to compare mosaic with painting or sculpture. The ceramics market can be charted with precision because institutional infrastructure produced, over four decades, the data to chart it. Mosaic, treated as craft and therefore not worth systematically documenting, was not. The absence of data is the condition this report is designed to name, analyze, and argue the MME is positioned to begin correcting.
In 1974, Marc Chagall installed The Four Seasons in the plaza of the First National Bank of Chicago. He was eighty-seven years old and had been making art for more than sixty years. The work is roughly seventy feet long and fourteen feet high, composed of 128 mosaic panels surfaced in hand-chipped glass and stone tesserae in more than 250 colors. Chagall designed it as a gift to the city, a work in a medium he had made his own in the south of France through years of collaboration with the mosaicist Lino Melano, who began fabricating its panels under Chagall’s direction. It stands today in Chase Tower Plaza, walked past by millions of people every year, reproduced on Chicago tourism materials, acknowledged in every serious account of Chagall’s later career.
Now open any major scholarly monograph on Marc Chagall. Read the catalog raisonné. Work through the critical literature on his contribution to twentieth-century art. The paintings get the chapters. The stained glass at the Hadassah Hebrew University Medical Center gets its own substantial section; so do the Peace window at the United Nations and the axial-chapel windows at Reims Cathedral. The Four Seasons — the mosaic in Chicago — is present in the way you acknowledge something you are not sure how to categorize: carefully, at the edge of the frame, in a photograph caption rather than an argument.
This is not a case of a minor work being underappreciated. The Four Seasons is a major work by one of the twentieth century’s most famous artists, executed in a medium he had deliberately chosen and studied, and installed permanently in one of the most visible public spaces in the United States. The scholarship’s treatment of it is not an oversight. It is a reflex — the reflex that says painting is where the argument lives, and mosaic is where you note a decorative flourish and move on. Even for Chagall. Even in 1974. Even in 2026.
This reflex has a price. It is a price paid by every mosaic artist who has ever negotiated a commission fee against the assumption that their medium is a craft rather than a fine art. It is paid by every estate administrator who has valued a mosaic under a building insurance policy because no fine art comparables existed. It is paid by the field as a whole, in the compounding arithmetic of undervaluation — every low appraisal feeding the next negotiation, every absent auction category making the next gallery conversation harder, the absence of institutional data perpetuating itself through every transaction that depends on institutional data to price correctly.
The ceramics market tells us what happens when that changes. Not gradually, not mysteriously, but through specific, traceable institutional decisions that took four decades and produced measurable results. This report documents that trajectory, measures the gap between where mosaic stands and where ceramics now is, and makes the case for what the Museum of Mosaic Environments is positioned to do about it — for investors who understand asymmetric positioning, and for artists who have spent careers inside a market that has systematically failed to price their work.
Lucie Rie had been making pottery for fifty years by the time the Victoria and Albert Museum mounted her retrospective in 1982. She had trained at the Kunstgewerbeschule in Vienna, fled Austria in 1938, established a studio in Albion Mews in London, and spent four decades producing stoneware and porcelain vessels of technical and formal refinement that a small community of collectors understood to be exceptional and a much larger community of critics understood to be, at best, distinguished craft. She was not obscure. Her work had been shown widely, collected seriously, and written about with genuine admiration in the studio pottery press. She was simply in the wrong category — not because of anything her work lacked, but because the institutions that governed fine art had not yet said otherwise with their full weight. An Arts Council retrospective in 1967 had begun the argument; the V&A finished it.
The V&A said otherwise in 1982, hosting a retrospective that had originated at the Sainsbury Centre in Norwich. The retrospective was not a discovery; it was a reclassification. It placed her vessels in a fine art institutional context, produced a scholarly catalogue, and generated press coverage that reached collectors who had never looked at studio pottery before. The market response was not immediate — these things never are — but it was directional. Prices began to move. Auction houses began paying attention. By the time Rie died in 1995, her work was selling for multiples of its 1970s prices. By the mid-2010s, her finest pieces had crossed six figures: Phillips sold a 1978 footed bowl for $212,500 in 2016, a footed bowl set a world auction record of €406,800 at Bonhams Cornette de Saint Cyr in December 2023, and Phillips New York sold a late-1970s footed bowl for $422,910 in December 2024 — prices that would have seemed hallucinatory to anyone who had bought her bowls in the 1970s.
The pots had not changed. The story the institutions told about them had changed — and in the art market, the institutional story is the price.
Grayson Perry collected the Turner Prize in 2003 wearing a pale blue frock with a Peter Pan collar. He accepted it for ceramic works — not paintings, not sculpture in any medium the prize committee had favored before, but ceramic pots, decorated with images that were complex, disturbing, and technically extraordinary. The Turner judges called the work “direct and uncompromising.” Perry called it, with characteristic precision, “a bit of a laugh.” His ceramic works then began selling at auction for sums that bore no resemblance to the prices they had commanded before that evening at Tate Britain. Vases that were selling for up to £25,000 at the time of the prize were, by 2017, selling through Christie’s and Phillips for hundreds of thousands — £632,750 for I Want To Be An Artist at Christie’s London in 2017, £150,000 at Phillips London in 2019, and £443,250 for a pair of vases at Christie’s London in 2019.
The Turner Prize provided something that decades of critical admiration had not: a dated, public, institutional event at which the frame shifted. Collectors who had not known what to do with ceramic art before 2003 now had a purchase — a named prize, a named institution, a canonical moment they could point to when explaining why the work mattered. The institutional story became the collector’s story, which became the auction estimate, which became the comparables, which became the appraisal value, which became the insurance figure, which became the next collector’s reference point. The mechanism is not metaphorical. It is financial infrastructure, and it runs on institutional decisions.
The campus of the National Autonomous University of Mexico carries the largest concentration of twentieth-century mosaic ambition in the Americas, and two canonical artists made it. Juan O’Gorman wrapped the Central Library, inaugurated in 1956, on four sides in a stone mosaic of roughly four thousand square meters — Representación histórica de la cultura, among the largest mosaics in the world. Diego Rivera contracted in 1952 to cover the Estadio Olímpico Universitario at the same campus in stone-mosaic high relief, worked on it through 1954, completed only the central section over the main entrance, and called that work — not his frescoes — the most important achievement of his life as an artist. These are not decorative flourishes. They are programmatic, politically complex, formally extraordinary works in a medium Rivera had chosen deliberately, at the end of a career during which he had become one of the most discussed artists in the world.
Ask anyone who has taken a survey course in twentieth-century Latin American art what Rivera’s major works are. They will tell you about the Detroit Industry Murals. They will tell you about Man at the Crossroads, the Rockefeller Center commission that was destroyed and repainted in Mexico City. They will describe the Chapingo Chapel frescoes, the National Palace cycles, the History of Mexico. The UNAM mosaics, if they appear at all, appear in the way Chagall’s Four Seasons appears in the Chagall literature: acknowledged, then passed over. Rivera’s mosaic work has been the subject of less critical scholarship than almost any equivalent output by any artist of his stature. The explanation is not quality, and it is not accessibility — the UNAM campus is one of the most visited destinations in Mexico City. The explanation is the category. Rivera’s paintings are art. Rivera’s mosaics are, institutionally, something else: building decoration, architecture, public art in the diminished sense that phrase often carries. The medium determines the frame, and the frame determines what the scholarship thinks it is looking at.
This is the condition of mosaic in 2026: a medium practiced at the highest level by artists of documented historical significance, installed in locations of maximum public visibility, and still routinely treated by the institutional apparatus as peripheral to the central story. Not because the work is peripheral. Because the story was written by people who did not know what to do with the medium, and the institutions that could have corrected that have not yet done so.
The most direct evidence of mosaic’s institutional valuation is not an auction result or an appraisal figure. It is what artists are paid to make it. And the structure of how mosaic commissions are priced reveals, with a precision that no survey data could match, how the classification of mosaic as craft rather than fine art operates as a direct economic mechanism in the lives of working artists.
Consider the arithmetic of a public art commission. The U.S. General Services Administration has reserved a percentage of federal construction budgets for art since 1963; its Art in Architecture program, established in 1972, allocates at least one-half of one percent of a building’s estimated construction cost to artwork. This allocation is consistent regardless of medium — a painting and a mosaic at the same scale, in the same building, would receive the same total budget. What differs is what that budget actually pays for. A large-scale painting requires canvas, paint, and the artist’s time. A large-scale mosaic of equivalent square footage requires tesserae — glass, stone, smalti, vitreous tile — adhesives, backing materials, grout, armatures, and often a team of skilled assistants for installation; the physical materials alone can run from a few dollars to more than three hundred dollars per square foot — for stone and smalti work, an outlay approaching the entire fabrication labor charge — before a single assistant is paid or a single panel is installed. The artist’s design fee, the compensation for the creative and intellectual labor of the work, is whatever is left after the materials are paid for.
This is not a policy written to disadvantage mosaic artists. It is an accounting structure that was designed for painting and applied without adjustment to a medium with categorically different material requirements. The result is that mosaic artists working within identical public art budget frameworks routinely take home a smaller percentage of the total commission as artist compensation than their painting equivalents — not because their work is valued less in any explicit sense, but because the arithmetic of the medium is invisible to the structure. The structural discount is not deliberate. It is automatic. Which makes it harder to name and harder to fix.
The secondary market amplifies the injury. A painting commission creates a work that will be appraised as fine art and scheduled on a fine art policy at appraised value, and potentially resold on the secondary market, generating future income for the artist through resale royalties and reputation effects that compound over years. A mosaic commission — classified in most institutional contexts as a building installation or public decoration — is, under standard property-insurance practice, part of the building it is bonded to: covered as a fixture under the building’s property policy and valued at replacement cost — the cost of physical reproduction — unless someone makes the affirmative decision to schedule it as fine art at an appraised value. No one has published a count of how often that decision is made for mosaic. That absence is consistent with every other absence this report records. The artist is paid once, for a permanent, site-specific work that the commissioning institution owns and values as a fixture rather than as a fine art acquisition. The economic difference between those two framings is not marginal. For an accomplished artist working over a forty-year career, it is the difference between an estate with quantifiable market value and one that defaults, at the moment of administration, to an appraisal that reflects the cost of tile and grout.
Here is a thought experiment that is not hypothetical. Think of two artists, both of whom have spent forty years producing large-scale work — technically demanding, conceptually coherent, publicly visible, widely respected within their respective fields. One works in ceramics. One works in mosaic. Their careers have run in parallel: similar numbers of commissions, similar institutional affiliations, similar critical recognition within their specialist communities. The ceramics artist’s work, over those forty years, has been progressively revalued by the sequence of institutional decisions described in Part I. The mosaic artist’s work has not, because no equivalent sequence has occurred for the medium. When both estates are administered — when both artists die and leave behind a life’s work to be valued for inheritance, for sale, for institutional donation — the ceramics estate will be appraised using methodology that has been developed, published, and tested over four decades of fine art market engagement. The mosaic estate will be appraised by whoever the family can find, using judgment formed in the absence of published standards, and will default to a valuation that reflects the medium’s institutional status rather than the work’s quality.
The difference in those two appraisals is not a matter of technical complexity. It is the direct economic consequence of forty years of institutional absence. The work is the same quality. The career is equivalent. The market outcomes are not, and they are not because one medium has an institutional history that the other does not. This is the precise cost of having no champion.
And the cost compounds. It does not stay still at the moment of estate administration. The undervalued appraisal feeds into the estate tax calculation. The estate tax calculation shapes what the family can retain and what must be sold. The sale, if it happens at all, happens at a price that reflects the appraiser’s methodology. That price becomes the comparables reference for the next artist who tries to sell a mosaic work, or the next institution that tries to insure one, or the next commissioning body that tries to decide what a mosaic is worth. Every undervaluation is the raw material for the next one. The compound arithmetic of institutional absence is not a figure anyone has calculated for the mosaic field, because no one has maintained the data needed to calculate it. That absence of data is the mechanism of the undervaluation, working invisibly, year after year.
This report has been forced, at several points, to acknowledge the limits of what can be documented with precision. The precise wage gap between mosaic artists and painting artists does not exist as a published figure. The average commission discount for mosaic relative to painting is not in any database. The estate valuation differential between ceramic and mosaic artists cannot be measured because no one has produced the data needed to measure it. In a document that values precision, these absences are frustrating to report.
But they are not failures of the research. They are the research. They are what institutional marginalization looks like, measured in the absence of the bureaucratic infrastructure that would quantify it. The ceramics market can be analyzed with precision because institutions — museums, auction houses, appraisal bodies, galleries — treated ceramics as worth documenting. The data exists because the institutions decided the medium was worth the record-keeping. Mosaic, classified as craft, was not granted that institutional attention, and the documentation that would quantify its inequities was never produced. The absence of the data is the same absence that produced the undervaluation. They are the same condition, visible at different scales.
The MME’s establishment of a commissioning record, a published fee schedule, an acquisition policy with recorded purchase prices, and an annual Equity and Accountability Report documenting what it pays and what it acquires will be the first systematic data generation the mosaic field has had. This is not an administrative byproduct of the museum’s operation. It is one of its most significant scholarly and economic contributions — the beginning of a record that will make future analysis possible and future correction measurable.
The mechanism by which a museum creates market value is not metaphorical or vague. It is specific, traceable, and has operated identically every time the art market has moved a medium from institutional exclusion to fine art recognition. It works through a small number of concrete institutional actions, each of which sends a signal that is legible to market participants, and those signals accumulate into a new institutional story, and the story becomes the price.
Acquisition at a published price is the most powerful single signal in the sequence. When a museum acquires a mosaic work — buys it, records the price in its public collection database, includes it in its next annual report — that price is no longer just a transaction. It is a comparable. Appraisers reference it. Collectors use it to calibrate offers. Auction houses use it to set estimates. Estate administrators use it to anchor valuations. Insurance adjusters use it to write policies. The price does not stay still in the record. It propagates through every subsequent transaction that needs a reference point for what a mosaic work is worth. A museum that acquires mosaic works at prices that reflect fine art valuations, and publishes those acquisition prices, is not merely buying art. It is manufacturing the data that the mosaic market has never had.
Exhibition and catalogue production is the second signal. A museum catalogue — peer-reviewed, with scholarly essays that contextualize work within art history, distributed through academic and museum channels — is an appraisal document in intellectual form. It does not merely argue that the work is significant. It demonstrates institutional consensus that the significance is established enough to document. Collectors and appraisers treat catalogue documentation as a legitimacy credential. Insurance adjusters factor it into valuations. The MME’s catalogue program will produce the intellectual infrastructure that the mosaic field currently lacks and that every comparable transition into fine art status has required.
Published commission fees are the third signal, and they operate differently from the first two: they set a floor. If the MME publicly pays mosaic artists fees benchmarked against equivalent painting commissions — separating the artist’s design and execution fee from material costs, as any honest accounting of creative labor requires — it establishes a reference point. Subsequent commissioning bodies will be asked to meet it. Artists will have something to point to when negotiating with clients who have always assumed that the absence of comparables means any price is acceptable. Publishing what an institution pays is advocacy in the form of institutional practice, and it is also market data, and those two things are the same thing.
Fine art insurance and appraisal engagement is the fourth signal. When the MME insures its collection under fine art policies — and when it works with the American Society of Appraisers and the Appraisers Association of America to develop published mosaic-specific valuation methodology — it creates the standards that no appraiser currently has access to. This is specialized, unglamorous, institution-scale work. It is also the kind of work that made it possible, eventually, to appraise a Lucie Rie bowl at six figures rather than at decorative arts replacement cost. The appraisal standards come last in the sequence, after the acquisitions and the exhibitions and the galleries have established the market. But they are the capstone of the process — the moment at which the institutional story becomes permanently encoded in professional practice.
The ceramics analogy is instructive for investors in one particular and precise way. The early institutional movers — the V&A’s decision to mount the Rie retrospective, Bonhams’ decision to run dedicated contemporary-ceramics auctions from 1988 and to create the first contemporary design department in 1996, Victoria Miro’s decision to represent Perry in 2003, when his vases still sold for a fraction of the six-figure sums they would command at auction from 2017 — did not make those decisions because the market had confirmed the thesis. They made them because they judged the quality and historical significance of the work to be sufficient to merit institutional attention, and they were willing to act on that judgment before the market caught up. The market followed because the institutions moved. That is the sequence. The institution does not wait for the market. The market waits for the institution.
The MME is not an investment fund. It is not making bets on individual artists. But its relationship to the mosaic market is structurally identical to the position of those early institutional movers in the ceramics story: it is the institution that will initiate the first stage of the fine art recognition sequence for a medium that has not yet had one. Investors who participate in that sequence — through the MME Foundation’s capital campaign or through MME Studios’ Series A structure — are not entering an established market. They are investing in the institution that will establish it.
The asymmetry is genuine and it is worth stating plainly. A medium with a documented history longer than oil painting, a practitioner community organized into professional associations on four continents — the Society of American Mosaic Artists, the Association Internationale des Mosaïstes Contemporains in Ravenna, the British Association for Modern Mosaic, and the Mosaic Association of Australia and New Zealand, alongside working studios across Latin America and Iberia, and a body of extant work of acknowledged aesthetic and historical significance — that medium’s market position reflects institutional absence, not intrinsic quality. The gap between where mosaic is valued and where it would be valued with appropriate institutional infrastructure is not a rounding error. It is the accumulated result of five centuries of post-Renaissance categorization that placed mosaic outside the frame that generates market value. The institution that changes that frame changes the market. That is what institutions are for, and it is what they are worth.
These are not aspirational positions. They are operational commitments with direct market consequences, each designed to generate the specific type of data or signal that the sequence requires.
Marc Chagall’s Four Seasons stands in a Chicago plaza, walked past by millions of people, and the scholarship on his work treats it as peripheral. Diego Rivera called his stadium mosaic at the UNAM the most important achievement of his life as an artist, and the survey courses that taught generations of students about Rivera taught them about frescoes. The artists who covered the walls of Hagia Sophia with the most technically complex and visually extraordinary pictorial program of the medieval world — their names are not in any record, because recording the names of people who made mosaics was not considered, at the time, worth the effort of inscription. The logic of institutional erasure is consistent across centuries and continents: the medium is always the reason, and the reason is always the category.
The ceramics market spent four decades dismantling that logic for its medium. It did not do it through argument alone — through critics writing that Lucie Rie’s bowls were as good as paintings, which they were, and had always been. It did it through institutions taking specific actions that sent specific signals that market participants acted on: the V&A retrospective in 1982, the dedicated ceramics auctions at Bonhams from 1988, the Design sale categories created in the 1990s, the Turner Prize in 2003, the blue-chip galleries, the scholarly monographs, the acquisition records, the appraisal standards. Each step was institutional. Each step changed the story. The story changed the price.
Mosaic has not had those institutions. The Chagall Four Seasons has never had a major museum retrospective organized around it as a mosaic. The UNAM program — O’Gorman’s library and Rivera’s stadium alike — has never been the subject of a catalog that placed the mosaic work within the critical apparatus applied to the same artists’ paintings. The contemporary practitioners — the Sonia Kings, the artists working in Ravenna and in studios across Europe and the Iberian Peninsula and Latin America and Australia — have no auction category, no blue-chip gallery, no published appraisal standard, no institutional acquisition policy that says: this medium, in this context, is worth what fine art is worth.
The Museum of Mosaic Environments is the institution that begins to change that. Not by arguing that mosaic is as good as painting — that argument has been available for as long as anyone has been making mosaics, and it has not been sufficient. But by doing what institutions do: acquiring works at published prices that become comparables, commissioning artists at fees that become reference points, producing scholarship that becomes the intellectual infrastructure for appraisal, insuring works at values that reflect their significance rather than their material reproduction cost, and publishing a record of all of it so that the next appraiser, the next collector, the next commissioning institution has somewhere to start.
The case for the museum is inseparable from the case for the market. The market does not correct itself in the absence of institutional action. The Chagall Four Seasons will remain in the corner of the frame until a museum puts it at the center. That is what institutions are for. It is also, precisely, what they are worth.
What Institutions Are Worth builds directly on the exclusion framework established in Designed to Fail, extending its institutional analysis into the specific economic mechanisms through which categorical misclassification produces compounding market harm.
The Mosaic Record provides the baseline market documentation that this report argues is structurally absent — the two reports read together as diagnosis and evidence.
The Unpaid Canvas and Made by Hand examine the compensation and labor dimensions of the commission structure analyzed in §2.2; each extends the arithmetic of undervaluation into artist-specific economic consequences.
Public Art and the Diminished Sense addresses the public commission framework and the valuation consequences of the “public decoration” classification discussed here.
Forensic Examination of Aesthetic Value in the Market carries the market valuation argument further, with direct analysis of how aesthetic value is priced in the absence of institutional infrastructure.
The following table consolidates primary data points cited throughout this report for use in downstream communications, investor materials, and presentations.
Artnet Analytics. Lucie Rie, Hans Coper, and Grayson Perry auction results databases. artnet.com
Birks, T. (1987). Lucie Rie. Alphabooks; rev. ed. Marston House, 1994.
Birks, T. (1983). Hans Coper. Collins; rev. ed. Marston House, 1991.
Bonhams. Contemporary ceramics and design sale records, 1988–2025. bonhams.com; Christie’s and Phillips. Design sale categories and published results. christies.com, phillips.com
de Waal, E. (2010). The Hare with Amber Eyes. Chatto & Windus.
Serpentine Gallery. Grayson Perry: The Most Popular Art Exhibition Ever! (8 June – 10 September 2017). serpentinegalleries.org
Victoria and Albert Museum. Lucie Rie retrospective (1982). V&A Archives, London.
Phillips. Ceramic and design sale records, 2010–2025. phillips.com
General Services Administration. Art in Architecture Program. gsa.gov/artinarchitecture
National Endowment for the Arts. Public Art Program documentation and grant records. arts.gov
Americans for the Arts. Public Art Network Year in Review. americansforthearts.org
Society of American Mosaic Artists. Artist Commission and Pricing Resources. americanmosaics.org
American Society of Appraisers. Personal Property Specialties — Fine Art. appraisers.org
Appraisers Association of America. Fine Art Specialty Designation. appraisersassociation.org
Velthuis, O. (2005). Talking Prices: Symbolic Meanings of Prices on the Market for Contemporary Art. Princeton University Press.
Art Basel & UBS (2025). The Art Basel and UBS Art Market Report. artbasel.com / ubs.com
Bocart, F., Ghysels, E., & Hafner, C. “Glass Ceilings in the Art Market.” Cited by the National Museum of Women in the Arts.
Mei, J., & Moses, M. (2002). Art as an Investment and the Underperformance of Masterpieces. American Economic Review, 92(5), 1656–1668.
Miles, H. Mosaics in the History of Art (or Not as the Case May Be). helenmilesmosaics.org
Miles, H. Contemporary Mosaics: Learning Lessons from Ceramics. helenmilesmosaics.org
Society of American Mosaic Artists. Institutional history and founding documentation. americanmosaics.org
Festival of Contemporary Mosaic, Ravenna. International competition records. ravennamosaici.it
Encyclopaedia Britannica. Mosaic (art). britannica.com
Pliny the Elder. Natural History, Book XXXVI (on Sosus of Pergamon). Trans. D.E. Eichholz. Loeb Classical Library, Harvard University Press.
Art Institute of Chicago. Marc Chagall: The Four Seasons. Documentation and conservation records.
Universidad Nacional Autónoma de México. Central Library mosaic program documentation (Juan O’Gorman, Representación histórica de la cultura) and Estadio Olímpico Universitario relief documentation (Diego Rivera). unam.mx and gaceta.unam.mx
Hamill, P. (1999). Diego Rivera. Harry N. Abrams. [Rivera’s account of the UNAM commission.]
This report was developed through an iterative, fact-checked, and edited collaborative research process between Rachael Que Vargas and Anthropic’s Claude (in two roles — long-form research and document operations). The questions, institutional framework, and editorial judgment are the author’s; the research synthesis and structural development are collaborative.
© 2026 Rachael Que Vargas / Museum of Mosaic Environments. Licensed under Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0). You may share and adapt this work for non-commercial purposes with attribution. Full license: https://creativecommons.org/licenses/by-nc/4.0/