Progress techniki v epochu eneolita na Jugo-Vostoke Evropy (po materialam zemledel'českich kul'tur Bolgarii). Technological progress in the Chalcolithic of Southeastern Europe (based on early agricultural sites in Bulgaria) - Skakun, Natalija Nikolaevna (Archeologičeskie Vesti, 6 (1999), 1999)