Nonlinear Oscillations of a Spring Pendulum at the 1: 1: 2 Resonance by Normal Form Methods. - Victor F. Edneral; Alexander G. Petrov (Math. Comput. Sci., 2020)

Orthogonal-symplectic matrices and their parametric representation. - Alexander B. Batkhin; Alexander G. Petrov (J. Symb. Comput., 2025)