1. A. Lyapunov, General Problem on the Stability of Motion, Vol. 2 (Nauka, Moscow, 1956). [in Russian]
2. N. Yerugin, A Book for Reading on the General Course of Differential Equations (Nauka i Tekhnika, Minsk, 1979). [in Russian]
3. Approximate methods for solving nonlinear initial boundary-value problems based on special constructions of series
4. S. S. Titov (2003) Proc. of the Steklov Institute of Mathematics S2, S148–S172.
5. Application of special coordinated series to the solution of nonlinear partial differential equations in bounded domains