Pepperberg, I. M. Numerical abilities of grey parrots: Comparisons with apes and children / Irene M. Pepperberg. Quo vadis, behavioural biology? : past, present, and future of an evolving science ; international symposium of the Humboldt-Universität zu Berlin and the German National Academy of Sciences Leopoldina, Berlin, April 30 to May 4, 2009 ; with 2 tables.(2013).
Cytowanie według stylu Chicago (wyd. 17)Pepperberg, Irene M. "Numerical Abilities of Grey Parrots: Comparisons with Apes and Children / Irene M. Pepperberg." Quo Vadis, Behavioural Biology? : Past, Present, and Future of an Evolving Science ; International Symposium of the Humboldt-Universität Zu Berlin and the German National Academy of Sciences Leopoldina, Berlin, April 30 to May 4, 2009 ; with 2 Tables.(2013) .
Cytowanie według stylu MLA (wyd. 8)Pepperberg, Irene M. "Numerical Abilities of Grey Parrots: Comparisons with Apes and Children / Irene M. Pepperberg." Quo Vadis, Behavioural Biology? : Past, Present, and Future of an Evolving Science ; International Symposium of the Humboldt-Universität Zu Berlin and the German National Academy of Sciences Leopoldina, Berlin, April 30 to May 4, 2009 ; with 2 Tables.(2013), .