Lagoda, V.A. and Parasyuk, I.O. 2013. Theorem on the existence of an invariant section over $\mathbb{R}^m$ for the indefinite monotone system in $\mathbb{R}^m \times \mathbb{R}^n$. Ukrains’kyi Matematychnyi Zhurnal. 65, 1 (Jan. 2013), 103-118.