KHACHATURYAN, A. . Necessary Conditions for Optimal Permissible Placement by the height of the Transitive Directed Tree with One Root (part second). Mathematical Problems of Computer Science, [S. l.], v. 37, p. 102–107, 2021. Disponível em: http://mpcs.sci.am/index.php/mpcs/article/view/259. Acesso em: 3 may. 2024.