A Guide to Planning and Conducting Environmental Study Area Workshops / 
National Education Association & U.S. Department of the Interior. National Park Service. 
 - Washington, D.C. :  National Park Service,  1972. 
 - 50 p. ;  il. ;  27 cm. 
<br/><br/>Referencias bibliográficas: pp. 49-50. 
<br/><br/><br/>Inglés 
<br/><br/><label>Dewey Class. No.: </label>363.70071