^Figure data, uncorrected absorbance curve fits, from Hart NS, Partridge JC, Bennett ATD and Cuthill IC (2000) Visual pigments, cone oil droplets and ocular media in four species of estrildid finch. Journal of Comparative Physiology A186 (7-8): 681-694.
^Jameson KA, Highnote SM, Wasserman LM. Richer color experience in observers with multiple photopigment opsin genes. Psychon Bull Rev. 2001;8(2):244-261.