Abstract-concept learning carryover effects from the initial training set in pigeons (Columba livia)
Journal of Comparative Psychology (2009) - Comment
pubmed: 19236147  doi: 10.1037/a0013126  issn: 0735-7036  issn: 1939-2087 

Tamo Nakamura, Anthony A. Wright, Jeffrey S. Katz, Kent D. Bodily, Bradley R. Sturz