National parks for the future :  an appraisal of the national parks as they begin their second century in a changing America / 
Conservation Foundation. 
 - Washington, D. C. :  The Conservation Foundation,  1972. 
 - 254 p. ;  23 cm. 
<br/><br/>p. 254. 
<br/><br/><label>Subjects--Topical Terms: </label><br/>National parks and reserves--United States.