Henao-Duque, A. M., and C. Ceballos. “Sex-Related Head Size and Shape Dimorphism in Mapaná Snakes (Bothrops Asper) Kept in Captivity”. Revista Colombiana De Ciencias Pecuarias, vol. 26, no. 3, Sept. 2013, pp. 201-10, doi:10.17533/udea.rccp.324830.