2 citations to https://www.mathnet.ru/rus/basm568

1. Victor Orlov, Magomedyusuf Gasanov, “The Maximum Domain for an Analytical Approximate Solution to a Nonlinear Differential Equation in the Neighborhood of a Moving Singular Point”, Axioms, 12:9 (2023), 844  
2. Victor Orlov, “Moving Singular Points and the Van der Pol Equation, as Well as the Uniqueness of Its Solution”, Mathematics, 11:4 (2023), 873