Ogienko 1974. [Trilobites of the Lower Ordovician.]. Ogienko, L.V.; Byalyi, V.I.; Kolosnitsyna, G.R.[Eds]. 1-207, pls 1-35., [Biostratigraphy of the Cambrian and Ordovician deposits of the southern part of the Siberian platform.] Ministry of Geology, SSSR, VOSTSIBNIIGGMS, Nedra, Moscow., 1974: 1-8. Chapter pagination: 109-130