Ono, K. A. and Boness, Daryl J. 1991. "The influence El Niño on mother-pup behavior, pup ontogeny and sex ratios in the California sea lion." In Pinnipeds and El Niño: Responses to Environmental Stress. Trillmich, F. and Ono, K. A., editors. 185–192. New York: Springer-Verlag.