Handbook of agricultural charts 
/ U S Department of Agriculture 
 - Washington D C:   U S Department of Agriculture,   1976 
 - 169p. 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Science
<br/><br/><label>Subjects--Index Terms: </label>Pollution 
<br/><br/><label>Universal Decimal Class. No.: </label>R 63(084)  / L6