Verma, P.S, <br/><br/>
Concept of Ecology 

 - 1st /   1999. 
 - N.Delhi:  S.Chand & Company Ltd,  1999. 
 - 264 p. 
<br/><br/><label>ISBN: </label>812191681X 
<br/><br/><label>Subjects--Personal Names: </label><br/>Zoology, Ecology. 
<br/><br/><label>Dewey Class. No.: </label>574.5