Preserving of one-sided invariance in $\mathbb{R}^n$ with respect to systems of ordinary differential equations. Neliniini Kolyvannya, [S. l.], v. 5, n. 2, p. 278–285, 2002. Disponível em: https://twinhead.imath.kiev.ua/index.php/nosc/article/view/220. Acesso em: 22 jan. 2026.