*The 7th Ancient Civilizations in Bulgaria Golden Prehistoric Civilization, Civilization of Thracians and Macedonians, Hellenistic Civilization, Roman [Empire Civilization, Byzantine Civilization, Bulgarian Civilization, Islamic Civilization Bozhidar Dimitrov; Published by "KOM Foundation," Sofia, 2005 (108 p.)*Jordan Andreev, Ivan Lazarov, Plamen Pavlov, Koj koj e v srednovekovna Bălgarija, Sofia 1999.
*The 7th Ancient Civilizations in Bulgaria Golden Prehistoric Civilization, Civilization of Thracians and Macedonians, Hellenistic Civilization, Roman [Empire Civilization, Byzantine Civilization, Bulgarian Civilization, Islamic Civilization Bozhidar Dimitrov; Published by "KOM Foundation," Sofia, 2005 (108 p.)*Jordan Andreev, Ivan Lazarov, Plamen Pavlov, Koj koj e v srednovekovna Bălgarija, Sofia 1999.