Nikolov, Bogdan. Gradechnitza / auteur, Bogdan Nikolov ; photos, Roza Staneva. - Sofia : Naouka i Izkoustvo, 1974. - 1 v. (unpaged) : chiefly ill. (some col.) ; 19 x 21 cm. Includes bibliographical references. Subjects--Topical Terms: Neolithic period--Bulgaria--Gradeshnit︠s︡a Region.Copper age--Bulgaria--Gradeshnit︠s︡a Region.Excavations (Archaeology)--Bulgaria--Gradeshnit︠s︡a Region.Antiquities, Prehistoric--Bulgaria--Gradeshnit︠s︡a Region. Subjects--Geographic Terms: Gradeshnit︠s︡a Region (Bulgaria)--Antiquities.