1. Ermakov О.А., Levina М.А., Titov S.V., Levin B.А. mtDNA-based species identification of two widespread species of Roach (Cyprinidae, Rutilus) with extended sympatric zone. Inland Water Biology, 2017, vol. 10, no. 1, pp. 112–114.
2. Faerman M., Bar-Gal G.K., Boaretto E., Boeskorov G.G., Dokuchaev N.E., Ermakov O.A., Golenishchev F.N., Gubin S. V., Mintz E., Simonov E., Surin V.L., Titov S.V., Zanina O.G., Formozov N.A. DNA analysis of a 30,000-year-old Urocitellus glacialis from northeastern Siberia reveals phylogenetic relationships between ancient and present-day arctic ground squirrels. Scientific Reports, 2017, no. 7, pp. 42639. doi:10.1038/srep42639.
3. Levin B.A., Simonov E.P., Ermakov O.A., Levina M.A., Interesova E.A., Kovalchuk O.M., Malinina Y.A., Mamilov N.S., Mustafayev N.J., Pilin D.V., Pozdeev I.V., Prostakov N.I., Roubenyan H.R., Titov S.V., Vekhov D.A. Phylogeny and phylogeography of the roaches, genus Rutilus (Cyprinidae), at the Eastern part of its range as inferred from mtDNA analysis. Hydrobiologia, 2017, vol. 788(1), pp. 33–46.
4. Titov S.V., Kuzmin A.A., Naumov R.V., Ermakov O.A., Zaks S.S., Chernyshova O.V. The dynamics of habitats and the current state of settlements of ground squirrels in the right-bank regions of the Volga region. Penza: PSU, 2015. 126 p.
5. Ermakov O.A., Simonov E., Surin V.L., Titov S.V., Brandler O.V., Ivanova N.V., Borisenko A.V. Implications of hybridization, NUMTs, and overlooked diversity for DNA barcoding of Eurasian ground squirrels. PLoS ONE, 2015, vol. 10(1): e0117201.
6. Ermakov O.A., Fayzulin A.I., Zaks M.M., Kaibeleva E.I., Zaripova F.F. Distribution “western” and “eastern” forms of marsh frog Pelophylax ridibundus S.L. in the Samara and Saratov region (on data of analysis of mtDNA and nDNA). Izvestia of Samara Scientific Center of the Russian Academy of Sciences, 2014, vol. 16, no. 5 (1), pp. 409-412.
7. Ermakov A.S., Levin B.A., Ermakov O.A. Genetic diversity of Ukrainian brook lamprey Eudontomyzon mariae on north-eastern border of range inferred from mtDNA control region. XXI Century: Resumes of the Past and Challenges of the Present plus, 2014, vol. 2, no. 01 (17), pp. 17-21.
8. Ermakov O.A., Zaks M.M., Titov S.V. Diagnostics and distribution of the “western” and “eastern” forms of marsh frog Pelophylax ridibundus S. L. in the Penza province (on data of analysis of mtDNA cytochrome oxidase gene). Tambov University Reports. Series Natural and Technical Sciences, 2013, vol.18, no. 6, pp. 2999-3002.
9. Artaev O.N., Ermakov A.S., Ruchin A.B., Ermakov O.A., Levin B.A. Distribution of Ukrainian lamprey Eudontomyzon mariae (Berg, 1931) on north - eastern border of range. Tambov University Reports. Series Natural and Technical Sciences, 2013, vol. 18, no. 6, pp. 2975-2978.
10. Rumyantsev V.Yu., Ermakov O.A., Ilyin V.Yu., Dobrolyubov A.N., Soldatov M.S., Danilenko E.A. On the history and modern state of the steppe marmot (Marmota bobak Müll.) in Penza oblast. Arid Ecosystems, 2012, vol. 18, no. 2 (51), pp. 62–73.
11. Ermakov O.A., Surin V.L., Titov S.V. Genetic diversity and differentiation of the Speckled Ground Squirrel inferred from sequencing of mtDNA control region. Izvestiya of Penza State Pedagogical University named after V.G. Belinsky. Natural Sciences, 2011, no. 25, pp. 176–180.
12. Nikol’skii A.A., Ermakov O.A., Titov S.V. Geographic variability of little ground squirrel (Spermophilus pygmaeus): a bioacoustic analysis. Zoological Journal, 2007, vol. 86 (11), pp. 1379-1388.
13. Ermakov O.A., Titov S.V., Savinetsky A.B., Surin V.L., Zborovsky S.S., Lyapunova E.A., Brandler O.V., Formozov N.A. Molecular-genetic and paleoecological arguments for conspecificity of little (Spermophilus pygmaeus) and Caucasian mountain (S. musicus) ground squirrels. Zoological Journal, 2006, vol. 85 (12), pp. 1474-1483.
14. Ermakov O.A., Titov S.V., Surin V.L., Formozov N.A. Molecular genetic study of maternal and paternal liniages of hybridization of ground squirrels (Spermophilus: Rodentia, Seiuridae). Bulletin of Moscow Society of Naturalists. Biological Series, 2006, vol. 111(5), pp. 30–35.
15. Ermakov O.A., Surin V.L., Titov S.V., Zborovskiy S.S., Formozov N.A. A search for Y-chromosomal species-specific markers and their use for hybridization analysis in ground squirrels (Spermophilus: Rodentia, sciuridae). Russian Journal of Genetics, 2006, vol. 42 (4), pp. 538-548.
16. Titov S.V., Ermakov O.A., Surin V.L., Formozov N.A., Kasatkin M.V., Shilova S.A., Shmyrov A.A. Molecular genetic and bioacoustic diagnostics russet (Spermophilus major Pallas, 1778) and yellow (S. fulvus Lichtenstein, 1823) ground squirrel from mixed colony. Bulletin of Moscow Society of Naturalists. Biological Series, 2005, vol. 110 (4), pp. 72–77.
17. Ermakov O.A., Titov S.V., Surin V.L., Tagiev A.F., Lukyanenko A.V., Formozov N.A. Study of hybridization in four species of ground squirrels (Spermophilus: Rodentia, Sciuridae) by molecular genetic methods. Russian Journal of Genetics, 2002, vol. 38 (7), pp. 950-964.