1. Avkhimovich, V.I., Tchibrikova, E.V., Obukhovskaya, T.G., et al., Middle and Upper Devonian miospore zonation of Eastern Europe, Bull. Cent. Rech. Explor.-Prod. Elf-Aquitaine, 1993, vol. 17, no. 1, pp. 79–147.
2. Floral assemblages in the Siluro–Devonian;H.P. Banks,1980
3. Esin, D., Ginter, M., Ivanov, A., et al., Vertebrate correlation of the Upper Devonian and Lower Carboniferous on the East European Platform, in CFS, Cour. Forschungsinst. Senckenberg (Final Report of IGCP, Project no. 328), 2000, no. 223, pp. 341–359.
4. Fortunatova, N.K., Zaitseva, E.L., and Kartseva, O.A., Structure of Devonian terrigenous complex and position of Middle and Upper Devonian boundary in western Tatarstan, Byull. MOIP. Otd.
Geol., 2013, vol. 88, no. 2, pp. 22–49.
5. Ivanov, A.O. and Kuzmin, A.V., Complexes of ichthyofauna and conodonts from Frasnian shallow-water deposits of Middle Timan, in Tez. Dokl. Vsesoyuz. Soveshch. “Geologiya devona Severo-Vostoka evropeiskoi chasti SSSR”, Syktyvkar, 2–4 aprelya 1991 g. (Proc. All-Union Conf. “Geology of the Devonian in the North-East of the European Part of the USSR”), Syktyvkar, 1991, pp. 24–25.