Blake Morton, F., Lee, Phyllis C., Buchanan-Smith, Hannah M., Brosnan, Sarah F., Thierry, Bernard, Paukner, Annika, de Waal, Frans B. M., Widness, Jane, Essler, Jennifer L., Weiss, Alexander, "Personality structure in brown capuchin monkeys (Sapajus apella): Comparisons with chimpanzees (Pan troglodytes), orangutans (Pongo spp.), and rhesus macaques (Macaca mulatta).", Journal of Comparative Psychology, 2013