Just found this:
Smyth J.R. Genetics of plumage, skin, and pigmentation in chickens. In: Crawford R.D, editor. Poultry breeding and genetics. Elsevier Science; New York, NY: 1990.
http://vision.berkeley.edu/wildsoet/Protocols/UsefulReferences/chicken_genetics-pp109-67.pdf

Have added it to "Helpful Links" but thought I'd let you know as the "Helpful Links" header is always at the top of the list anyway.