Popov, A. (2000). High mountain treeless zone of the Central Balkan National Park: Biological diversity and problems of its conservation. Pensoft.
Chicago-Zitierstil (17. Ausg.)Popov, Alexi. High Mountain Treeless Zone of the Central Balkan National Park: Biological Diversity and Problems of Its Conservation. Sofia: Pensoft, 2000.
MLA-Zitierstil (9. Ausg.)Popov, Alexi. High Mountain Treeless Zone of the Central Balkan National Park: Biological Diversity and Problems of Its Conservation. Pensoft, 2000.
Achtung: Diese Zitate sind unter Umständen nicht zu 100% korrekt.