Carya illinoinensis - Species account from the USDA Forest Service (misspelled as C. illinoensis on this site). www.fs.fed.us/database/feis/plants/tree/carill
Pecan Breeding and Genetics - Includes information and images of many cultivars, as well as species accounts for pecans and all other U.S. hickories. aggie-horticulture.tamu.edu/carya
