Fagen, Robert. <br/><br/>
Animal play behavior / 
Robert Fagen. 
 - New York :  Oxford University Press,  1981. 
 - 684 p. :  ill. ;  23 cm. 
<br/><br/>Includes index and bibliography : p. 62-652 
<br/><br/><label>ISBN: </label>0195027604 0195027612 (pbk.) 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Play behavior in animals.