Keramikata ot perioda na vizantijskoto vladičestvo v bălgarskite zemi (11-12 v.) i ot Vtoroto bălgarsko carstvo (kraja na 12-14 v.): osnovni priliki i razliki. (Pottery in the periods of Byzantine domination over Bulgarian territories (11th and 12th century) and the Second Bulgarian Kingdom (the late 12th to 14th century): general similatities and differences). - Borisov, Boris D. (2005)