Smil, Vaclav. <br/><br/>
Global ecology :  environmental change and social flexibility / 
Vaclav Smil. 
 - London :  Routledge,  1993. 
 - 240 pages ;  23 cm. 
<br/><br/> Includes bibliographical references and index. 
<br/><br/><label>ISBN: </label>0415098866