Depending on what group, there's a lot out there. Examples for for common ssp.: KEEPING and BREEDING SNAKES (Mattison),BREEDING and KEEPING SNAKES (Schmidt), KINGSNAKES and MILKSNAKES (Markel), THE CORN SNAKE MANUAL (Love). Bob Applegate wrote one on milksnakes. Most breeders here will gladly help too. REPTILES magazine is helpful also.