Science, Vol. 317, No. 5843. (7 September 2007), pp. 1360-1366.
Science, Vol. 312, No. 5776. (19 May 2006), pp. 1038-1040.
Am J Primatol, Vol. 64, No. 4. (December 2004), pp. 377-396.
J Comp Psychol, Vol. 119, No. 2. (May 2005), pp. 145-154.
Anim Behav, Vol. 61, No. 1. (January 2001), pp. 139-151.
Developmental Science, Vol. 7, No. 4. (2004), pp. 488-498.
Dev Sci, Vol. 7, No. 4. (September 2004), pp. 488-498.
Animal Cognition, Vol. 7, No. 4. (October 2004), pp. 213-215.
Animal Behaviour, Vol. 59, No. 4. (April 2000), pp. 771-785.
Dev Psychol, Vol. 41, No. 2. (March 2005), pp. 328-337.
Behav Brain Sci, Vol. 28, No. 5. (October 2005)
Cognition, Vol. In Press, Corrected Proof
Child Development, Vol. 70, No. 2. (r 1999), pp. 381-395.
Science, Vol. 304, No. 5677. (11 June 2004), pp. 1682-1683.
Behavioral and Brain Sciences, Vol. ?, No. ??-??. (In Press (2004))
Child Development, Vol. 70, No. 2. (1999), pp. 381-395.