@ARTICLE{Pisula_Wojciech_Play_2008,
 author={Pisula, Wojciech},
 number={No 2},
 journal={Polish Psychological Bulletin},
 howpublished={online},
 year={2008},
 publisher={Committee for Psychological Science PAS},
 title={Play and Exploration in Animals — A Comparative Analysis},
 URL={http://www.czasopisma.pan.pl/Content/107580/PDF-MASTER/6.pdf},
 doi={10.2478/v10059-008-0009-4},
}