Economics of outdoor recreation 
by Marion Clawson and Jack L. Knetsch.  
 - Baltimore  Johns Hopkins Press  c1966.  
 - xx, 328 p.  20 cm. 
<br/><br/><label>ISBN: </label>0801813026 9780801813023 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Recreaciâon al aire libre--Aspectos econâomicos--Estados Unidos.