R.  Bekchiev, ?A study of the Pselaphinae (Coleoptera, Staphylinidae) in the Rhodope Mountains (Bulgaria)?, in Biodiversity of Bulgaria 4. Biodiversity of Western Rhodopes (Bulgaria and Greece) II., P.  Beron, Ed. Sofia: Pensoft Publishers & National Museum of Natural History, Bulgarian Academy of Sciences, 2011, p. 267?278.

P.  Beron, ?Terrestrial cave invertebrates of the Vrachanska Planina Mountains?, ZooNotes, vol. Supplement 3, no. Faunistic diversity of Vrachanski Balkan Nature Park, pp. 185-230, 2016.

P.  Beron, ?Aperçu sur la composition, l'origine et la formation de la faune cavernicole de la Stara planina occidentale (Bulgarie)?, International Journal of Speleology, vol. 9, pp. 197-220, 1978.

P.  Beron, Petrov, B., and Stoev, P., ?The Invertebrate cave fauna of the Eastern Rhodopes (Bulgaria and Greece)?, in Biodiversity of Bulgaria 2: Biodiversity of Eastern Rhodopes (Bulgaria and Greece)., P.  Beron and Popov, A., Eds. Sofia: Pensoft Publishers & National Museum of Natural History, Bulgarian Academy of Sciences, 2004, pp. 791-822.

P.  Beron, Daaliev, T., and Jalov, A., Caves and Speleology in Bulgaria. Sofia: Pensoft Publishers, BFS & NMNH, 2006, p. 600.

P.  Beron, Cave fauna of Bulgaria. Sofia: East-West, 2015, p. 436.