Template:Pamouktchiev & Tchechmedjieva, 1987
- Pamouktchiev, A. & Tchechmedjieva, V. 1987. Палеонтоложки определител (безгръбначни) [Paleontological Guide to Fossils: Invertebrates]. Sofia University "St. Kliment Ohridski" Press, Sofia. 347 pp. (Bulgarian)