Sigafoos, Robert S. <br/><br/>
Vegetation of Northwestern North America, as an aid in interpretation of Geologic Data / 
by Robert S. Sigafoos. 
 -- Washington :   United States Government Printing Office,   1958 
 - P. 165-183 + map. -- 
 (Geological Survey Bulletin  ;  1061-E).
<br/><br/><label>Subjects--Topical Terms: </label><br/>Estados Unidos<br/>Fitogeografía
<br/><br/><label>Universal Decimal Class. No.: </label>581.9(73)