Ecogeographic and Morphometric Variation in the Mexican Pine Snake, Pituophis deppei (Squamata: Colubridae)
Luis Fernando Hidalgo-Licona, María Guadalupe Gutiérrez-Mayén, César Antonio Sandoval-Ruiz, Anibal Díaz de la Vega-Pérez, and Jorge Guillermo Chollet-Villalpando
Ichthyology & Herpetology 110: 690–704