1. Atlas verkhnepaleozoiskikh uglei Kuznetskogo basseina (Atlas of Upper Paleozoic Coals in the Kuznetsk Basin), Zvonarev, I.N., Ed., Novosibirsk: Nauka, 1966.
2. Beznosov, P.A., Snigirevskii, S.M., Naugol’nykh, S.V., and Lukshevich, E.V., The Upper Devonian delta plain deposits of North Timan, Vestn. IG Komi NTs UrO RAN, 2018, no.1(277), pp. 25–44. https://doi.org/10.19110/2221-1381-2018-1-25-44
3. Bray, P.S. and Anderson, K.B., Identification of Carboniferous (320 million years old) class Ic amber, Science, 2009, vol. 326(5949). P. 132‒134. https://doi.org/10.1126/science.1177539
4. Cheng, D.S. and Han, D.X., Petrography of the Devonian coals from China, Coal Geol Coal Explor., 1995, vol. 21(1), pp. 25‒28 [in Chinese with English abstract].
5. Chernov, A.A., Geological studies of the northern Timan region, in Nov. Ser. MOIP, 1947. no. 6(10), p. 96.