SHCHEGOLEV, S. A. A resonance case of the existence of solutions of a quasilinear second-order differential system, which are represented by Fourier series with slowly varying parameters. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 51, n. 2, p. 285–288, 1999. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/4612. Acesso em: 11 apr. 2025.