The performance of bonobos (Pan paniscus), chimpanzees (Pan troglodytes), and orangutans (Pongo pygmaeus) in two versions of an object-choice task
Journal of Comparative Psychology (2009) - Comment
pubmed: 19685972  doi: 10.1037/a0016222  issn: 0735-7036  issn: 1939-2087 

Nicholas J. Mulcahy, Josep Call