TY - JOUR A1 - Berkson, G. A1 - Ross, B. A. T1 - Factors to consider in a conservation program for Gibbons JF - C. R. Carpenter (Ed.) Behaviour, New York and Basel (S. Karger) 1969, pp. 43-47. Y1 - 1969 ER - TY - JOUR A1 - Mason, William A. A1 - Berkson, G. T1 - Conditions Influencing Vocal Responsiveness of Infant Chimpanzees JF - Science, Vol. 137 (No. 3524, July 1962), pp. 127-128. Y1 - 1962 N1 - Xeroxcopy ER -