Uncorrected absorbances of visual pigments of birds (alternative to File:Tetrachromaticpigments01.png) based on Pryke, Sarah R. (2007) Sexual selection of Ultraviolet and structural color signals in Reproductive biology and phylogeny of birds/volume 6a-6b edited by Barrie G.M. Jamieson. pages 1-40.  This book cites 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 for the data, curve fits, and method; online here.
Own work
Shyamal L. and others