Izvǎngradskite svetilišta v rimskata provincija Trakija (I-IV vek) = Extraurban Sanctuaries in the Roman Province of Thrace (1st – 4th Century) - Khristov, Ivan,‏ ‎ 1970-‏ (Universitetsko izdatelstvo "Sv. Kliment Ochridski", 2015)