Asa, Frank. <br/><br/>
Ecuadorian obsidian sources used for artifact production and methods for provenience assignments. 

 - Washington, DC-US :   Society for American Archaeology,   1994. 
 - p.257-277 :   il 
 - trimestral 
 - Vol.5, no.3(Sep.1994) 
 - Latin American Antiquity ;   vol.5,no.3 .
 - Estados Unidos.   Society for American Archaeology. .