SMITH, Robert L. <br/><br/>
Zones and zonal variations in welded Ash Flows / 
by Robert L. Smith . 
 -- Washington :   United States Government Printing Office,   1960 
 - P. 149-159 + 1 map. -- 
 (Geological Survey Professional Paper  ;  354-F).
<br/><br/><label>Subjects--Topical Terms: </label><br/>Geología
<br/><br/><label>Universal Decimal Class. No.: </label>55