Classic edition sources : 
Thomas A Easton 
 - 4th ed. 
 - New York :  McGraw-Hill,  2012 
 - 200 p.: 
<br/><br/> Includes index. 
<br/><br/><label>ISBN: </label>9780073527642 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Environment
<br/><br/><label>LC Class. No.: </label>GE105 .E27 2012