"...a BLB [black light bulb] has a thin coating of a visible wavelength (VIS) filter generally applied to the inner wall of the bulb" from "Part I: Lighting and its effects on color-grading diamonds"(PPT). AGA Task Force on Lighting and Color-Grading. Accredited Gemologists Association. 3 February 2010. Retrieved 27 March 2013. See also the 2009 report: "Part I: Lighting and its effects on color-grading diamonds"(PPT). AGA Task Force on Lighting and Color-Grading. Accredited Gemologists Association. 4 February 2009. Retrieved 20 April 2018.
books.google.com
"Invisible Signals". Proceedings of the United States Naval Institute. 45 (10). Annapolis, Maryland: U.S. Naval Institute: 1794–1796. October 1919. Retrieved 27 March 2013.
Rodgers, John, ed. (1920). "Secret signaling by light rays". Kline Geology Laboratory. American Journal of Science. 49. New Haven: Yale University: 214–216. Retrieved 27 March 2013.
cartage.org.lb
Williams, Robin; Gigi Williams (2002). "Wood, Professor Robert Williams". Pioneers of Invisible Radiation Photography. RMIT Online University, Melbourne, Australia. Retrieved January 16, 2013.
