Neuroscientist, Vol. 8, No. 1. (February 2002), pp. 6-11.
J Gen Psychol, Vol. 134, No. 2. (April 2007), pp. 199-216.
Nature (03 June 2007)
Proc Biol Sci, Vol. 270, No. 1523. (22 July 2003), pp. 1441-1446.
Cognitive Psychology, Vol. 49, No. 2. (September 2004), pp. 85-117.
Curr Biol, Vol. 15, No. 20. (25 October 2005), pp. 1855-1860.
Cognition, Vol. 97, No. 3. (October 2005), pp. 315-325.
Animal Cognition, Vol. 10, No. 4. (October 2007), pp. 429-437.
Proc Biol Sci, Vol. 274, No. 1620. (7 August 2007), pp. 1913-1918.
Biol Lett, Vol. 3, No. 4. (22 August 2007), pp. 360-364.
Curr Biol, Vol. 17, No. 19. (9 October 2007), pp. 1663-1668.
Current Biology, Vol. 17, No. 23. (4 December 2007), pp. R1004-R1005.
J Neurosci, Vol. 22, No. 23. (1 December 2002), pp. 10078-10082.
Science, Vol. 305, No. 5682. (16 July 2004), pp. 407-410.
Nature, Vol. 437, No. 7063., pp. 1357-1359.