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2. Aristotle. 1957. Peri aistheseos kai aistheton [On Sense and Sensible Objects]. In On the Soul, Parva naturalia, On Breath, bilingual Greek-English, ed. W. S. Hett. Cambridge: Harvard University Press.
3. Baumann, Urs, Narciso Silvestrini, and Klaus Stromer. 2011. Colour Order Systems in Art and Science. In https://www.colorsystem.com
4. Boutet, Claude. 1708. Traité de la peinture en mignature … auquel on a ajouté un petit traité de la peinture au pastel, avec la méthode de composer les pastels. The Hague: Louis and Henry van Dole. English translation, with a speculative essay on its authorship by Rolf G. Kuehni, available at: http://www.iscc-archive.org/pdf/TraitePastel.pdf. Accessed June 2021.
5. Boyle, Robert. 1664. Experiments and Considerations Touching Colours. London: Henry Herringman.