See:
- Janusz K. Kozlowski, Excavation in the Bacho Kiro Cave (Bulgaria): Final Report, PWN, Warszawa 1982
- Fred H. Smith, James C. Ahern, The Origins of Modern Humans: Biology Reconsidered, John Wiley & Sons, 2013
- Paul G. Bahn, Jean Vertut, Journey Through the Ice Age, University of California Press 1997