Verma,P.S. <br/><br/>
CONCEPT OF ECOLOGY 

 - Ist 
 - DELHI  S. Chand Company Limtied 
 - 264p. 
<br/><br/><label>ISBN: </label>812191681X 
<br/><br/><label>Dewey Class. No.: </label>577.05  / VER-CON