Menkо Y. P. Method of determining intervals of instability of quasiharmonic systems with a delayed argument. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 18, n. 2, p. 129–135, 1966. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/8727. Acesso em: 7 apr. 2025.