Sand and gravel extraction projects / 
United Nations Environment Programme. 
 - Nairobi, Kenya :  The Programme,  1990. 
 - 37 p. 
 - Environmental guidelines ;  no. 20 .
 - Environmental management guidelines ;  no. 20 .
<br/><br/> Title from cover. 
<br/><br/><label>LCCN: </label>90043089     
<br/><br/><label>Subjects--Corporate Names: </label><br/>United Nations--Environmental policy--Periodicals.
<br/><br/><label>Subjects--Topical Terms: </label><br/>Environmental policy--Periodicals.<br/>Sand and gravel plants--Environmental aspects.