Penchev, V. A Hoard of Copper (Billon) Scyphati from the First Half of the 13th Century Found Near Petrich. (Sofia, 2003).
Bilingual (English-Bulgarian) edition. ISBN: 954-8761-41-6.
Table of contents
Catalogue
Byzantine coins from 12th century
Bulgarian imitations (fist, second and third decades of 13th century)
Latin imitations of Constantinople
Latin imitations of Thessalonica
The Empire of Nicaea
The Empire of Thessalonica
Commentary