Botkin, Daniel B. <br/><br/>
Environmental studies :  Earth as a living planet / 
Daniel B. Botkin and Edward A. Keller 
 - 2nd ed. 
 - Colombus :  Merril Publishing Company,  1987 
 - 685 p. :  ill. ;  29 cm. 
<br/><br/><label>ISBN: </label>0675204623 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Ecology<br/>Pollution--Environmental aspects<br/>Conservation of natural resources