Animal play : evolutionary, comparative, and ecological perspectives 
edited by Marc Bekoff and John A. Byers 
 - 1st ed 
 - Cambridge  Cambridge University Press  1998 
 - xvi, 274 p. : ill. ; 24 cm 
<br/><br/> Includes bibliographical references and index 
<br/><br/><label>ISBN: </label>9780521583831 
<br/><br/><label>ISSN: </label>97022056 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Play behavior in animals
<br/><br/><label>Dewey Class. No.: </label>591.563 BEK