1. Menzel, R. & Backhaus, W. (1991) in The Perception on Colour, ed. Gouras, P. (CRC, Boca Raton, FL), pp. 262-293.
2. Birds, berries and UV
3. UV vision: a bird's eye view of feathers
4. Harosi, F. I. (1985) in The Visual System, eds. Fein, A. & Levine, J. S. (Liss, New York), pp. 41-55.