Pal, G. K.; Pal, Pravati (2001). „chapter 52”. Textbook of Practical Physiology (1st izd.). Chennai: Orient Blackswan. str. 387. ISBN978-81-250-2021-9. Pristupljeno 11 October 2013. »The human eye has the ability to respond to all the wavelengths of light from 400-700 nm. This is called the visible part of the spectrum.«
Buser, Pierre A.; Imbert, Michel (1992). Vision. MIT Press. str. 50. ISBN978-0-262-02336-8. Pristupljeno 11 October 2013. »Light is a special class of radiant energy embracing wavelengths between 400 and 700 nm (or mμ), or 4000 to 7000 Å.«
Rashed, R. (2007). „The Celestial Kinematics of Ibn al-Haytham”. Arabic Sciences and Philosophy (Cambridge University Press) 17 (1): 7-55 [19]. DOI:10.1017/S0957423907000355. »U njegovoj optici se „najmanje čestice svetlosti“, kako ih je nazivao, karakterišu samo onim svojstvima koja mogu biti geometrijski opisana i eksperimentalno proverena; one imaju nedostatak svih vidljivih osobina, ali poseduju energiju«(en)
