Book: "Full Spectrum: How The Science of Color Made Us Modern" by Adam Rogers
Book: "Rainbow" by Bauer, Marion Dane
Website: National Geographic,
https://education.nationalgeographic.org/resource/rainbow/
Website: NewScientist,
https://web.archive.org/web/20170711065726/https://www.newscientist.com/blogs/shortsharpscience/2011/10/third-and-fourth-order-rainbow.html
Webbook: "The Rainbow Bridge: Rainbows in Art, Myth, and Science" by Raymond L. Lee, Alistair B. Fraser
https://books.google.ca/books?id=kZcCtT1ZeaEC&pg=PA110&redir_esc=y#v=onepage&q&f=false
Website: BBC,
https://www.bbc.com/news/science-environment-15197774