KHACHATURYAN, A. . Necessary Conditions for Optimal Permissible Placement by the Height of the Transitive Directed Tree with One Root. Mathematical Problems of Computer Science, [S. l.], v. 36, p. 104–114, 2021. Disponível em: http://mpcs.sci.am/index.php/mpcs/article/view/272. Acesso em: 18 may. 2024.