History. 

 - Londres-ENK :   International Institute for Conservation,   1971. 
 - páginas 170-176 
 - Irregular 
 - Vol. 8, no. 2(Dec.1970-1971) 
 - Art and archaeology technical abstracts  ;   Vol. 8, no. 2 .
<br/><br/> Stone and masonry. 
<br/><br/><br/>Inglés.