Bonsall, Clive, Maria Gurova, Nedko Elenski, Georgi Ivanov, Aneta Bakamska, Georgi Ganetsovski, Radka Zlateva-Uzunova, and Vladimir Slavchev. “Tracing the Source of Obsidian from Prehistoric Sites in Bulgaria: Установяване произхода на обсидиана от праисторически обекти в България”. Bulgarian e-Journal of Archaeology | Българско е-Списание за Археология 7, no. 1 (June 26, 2017): 37-59. Accessed June 19, 2021. https://be-ja.org/index.php/journal/article/view/be-ja-7-1-2017-37-59.