D. Ivanov og M. Lazarova (2019). «Past climate and vegetation in Southeast Bulgaria — a study based on the late Miocene pollen record from the Tundzha Basin». Journal of Palaeogeography. 8. ISSN2524-4507. doi:10.1186/s42501-018-0019-x.
D. Ivanov og M. Lazarova (2019). «Past climate and vegetation in Southeast Bulgaria — a study based on the late Miocene pollen record from the Tundzha Basin». Journal of Palaeogeography. 8. ISSN2524-4507. doi:10.1186/s42501-018-0019-x.