Wolfgang Köhler
1925. The mentality of apes, transl. from the 2nd German edition by Ella Winter. London: Kegan, Trench and New York: Harcourt, Brace and World. Original was Intelligenzprüfungen an Anthropoiden, Berlin 1917. 2nd German edition was titled Intelligenzprüfungen an Menschenaffen, Berlin: Springer 1921. Liveright 1976 reprint: