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♦ 1Akre, Thomas S.B., et al. "Reproduction by female bullsnakes (Pituophis catenifer sayi) in the Nebraska Sandhills." Southwestern Naturalist 57.1 (2012): 58+. Academic OneFile. Web. 15 July 2014.
♦ 2PREY HANDLING AND DIET OF LOUISIANA PINE SNAKES (PITUOPHIS RUTHVENI) AND BLACK PINE SNAKES (P. MELANOLEUCUS LODINGI), WITH COM- PARISONS TO OTHER SELECTED COLUBRID SNAKES, D. Craig Rudolph, Shirley J. Burgdorf, Richard N. Conner, Christopher S. Collins, Daniel Saenz, Richard R. Schaefer, Toni Trees, C. Michael Duran, Marc Ealy, John G. Himes, Herpetological Natural History, 9(1), 2002, pages 57-62