by Shepet, I. P., Litvin, D. B.
Published in Journal of mathematical sciences (New York, N.Y.) (01.01.2022)

by Shamolin, M. V.
Published in Journal of mathematical sciences (New York, N.Y.) (16.10.2020)

by Frolova, S.V.
Published in Izvestiâ Saratovskogo universiteta. Novaâ seriâ. Seriâ Filosofiâ. Psihologiâ. Pedagogika (Online) (2009)

by Pyurko, V E, Khrystova, T E, Pyurko, O E, Kazakova, S M
Published in IOP conference series. Earth and environmental science (01.06.2022)

by Utkin, V.A., Krasnova, S.A., Akhobadze, A.G.
Published in 2008 International Workshop on Variable Structure Systems (01.06.2008)