Hansen, Wallace R.  1920- <br/><br/>
The black Canyon of the Gunnison : today and yesterday / 
by Wallace R. Hansen. 
 -- Washington :   United States Government Printing Office,   1965 
 - 76 p. -- 
 (Geological Survey Bulletin  ; 1191).
<br/><br/><label>Subjects--Topical Terms: </label><br/>Estados Unidos<br/>Geología
<br/><br/><label>Universal Decimal Class. No.: </label>55(73)