The nature of play  great apes and humans 
edited by Anthony D. Pellegrini, Peter K. Smith. 
 - New York  Guilford  c2005. 
 - x, 308 p.  ill., map  24 cm. 
<br/><br/>Includes bibliographical references and index. 
<br/><br/><label>ISBN: </label>1593851170 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Play--Psychological aspects.<br/>Psychology, Comparative<br/>Play behavior in animals.
<br/><br/><label>LC Class. No.: </label>BF717  / .N38 2005