BORZDYKO, V. I. Periodic solutions of “predator–prey” systems with continuous delay and periodic coefficients. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 62, n. 1, p. 15–28, 2010. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/2840. Acesso em: 5 dec. 2025.