R. J. Schusterman, C. R. Kastak, and D. Kastak, “The Cognitive Sea Lion: Meaning and Memory in the Laboratory and in Nature,” in The Cognitive Animal: Empirical and Theoretical Perspectives on Animal Cognition, edited by M. Bekoff, C. Allen, and G. M. Burghardt, 217–228 (Cambridge, MA: MIT Press, 2002).
