ILEA, Veronica. “Some Properties of Solutions to a Planar System of Nonlinear Differential Equations”. Studia Universitatis Babeș-Bolyai Mathematica 63, no. 2 (June 30, 2018): 225–234. Accessed January 19, 2026. https://studia.reviste.ubbcluj.ro/index.php/subbmathematica/article/view/2067.