Emets, O. A., S. I. Nedobachii, and RoskladkaО. V. 2003. “Irreducible System of Constraints for a General Polyhedron of Arrangements”. Ukrains’kyi Matematychnyi Zhurnal 55 (1), 3-11. https://umj.imath.kiev.ua/index.php/umj/article/view/3882.