Zalessky, M. D. 1929. O novykh iskopaemykh iz permskikh otlozhenii basselinov rek Kamyk, Vyatki i Beloi (New Fossils from Permian Deposits of the Basins of the Kama, Vyatka and Belay Rivers). Trudy obshchestva estestvoispytatelei pri Kazanskom universitet