My doctoral dissertation on the ceramics of early colonial San Salvador is now available if you have access to the UMI/Proquest dissertation database. I went the extra mile and gave them a pdf of my creation, so it is text searchable and has color imagery.
The citation is
Card, Jeb J.
2007 The Ceramics of Colonial Ciudad Vieja, El Salvador: Culture Contact and Social Change in Mesoamerica. Ph.D. dissertation, Tulane University. University Microfilms, Ann Arbor.