Verma, P.S. <br/><br/>
Environmental biology  (principles of ecology) 
P. S. Verma, V. K. Agarwal. 
 - New Delhi  S. Chand and Company  1993 
 - viii, 591p., ill.; 22cm. 
<br/><br/><label>Dewey Class. No.: </label>574  / V51E