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I found these two references listed, but I haven't seen copies of them:
Berg, L.S. (1912) "The Fishes of the Sari-Su and Nura in the Akmolinsky region" Ann.Zool.Mus.Acad.Sci. 17: in Russian
Vegetation in the region of Sary Su and Kon rivers (Akmolinsk Region), Proceedings of the soil and botanical expeditions to the study of colonized regions of Asiatic Russia, Part 2: Botanical studies in 1908, No. 11, Smirnov, VI, 1912. St. Petersburg, 260x185, 7 b/w figs, in Russian.