Livingston, John A. (1996). «other selves». In Vitek, William; Jackson, Wes (eds.). Rooted in the land: essays on community and place. Yale University Press. էջ 133. ISBN978-0-300-06961-7.
Gómez, Juan-Carlos & Martín-Andrade, Beatriz (2005). «Fantasy Play in Apes». In Pellegrini, Anthony D. & Smith, Peter K. (eds.). The nature of play: great apes and humans. Guilford Press. էջ 153. ISBN978-1-59385-117-0.
McCune, L. & Agayoff, J. (2002). «Pretending as representation». In Mitchell, Robert W. (ed.). Pretending and imagination in animals and children. Cambridge University Press. էջ 51. ISBN978-0-521-77030-9.(չաշխատող հղում)
Fouts, Roger S. (2008). «Foreword». In McMillan, Franklin D. (ed.). Mental Health and Well-Being in Animals. Wiley-Blackwell. էջեր 15–17. ISBN978-0-8138-0489-7.
Hillix, William A. & Rumbaugh, Duane M. (1998). «Language in Animals». In Greenberg, Gary & Haraway, Maury M. (eds.). Comparative psychology: a handbook. Taylor & Francis. էջ 841. ISBN978-0-8153-1281-9.