1. Beerli P (1994) Genetic Isolation and Calibration of an Average Protein Clock in Western Palearctic Water Frogs of the Aegean Region. University of Zurich, PhD Dissertation
2. Beerli P, Hotz H, Tunner HG, Heppich S, Uzzell T (1994) Two new water frog species from the Aegean islands Crete and Karpathos (Amphibia, Salentia, Ranidae). Notulae Naturae, Academy of Natural Sciences of Philadelphia 470:1–9
3. Berger L (1966) Biometrical studies on the population of green frogs from the environs of Poznan. Ann Zool 23(11):303–324
4. Berger L (1968) Morphology of the F1 generation of various crosses within Rana esculenta complex. Acta zoologica cracoviensia 13(13):301–324
5. Berger L (1990) On the origin of genetic systems in European water frog hybrids. Zoologica Poloniae 35:5–27