SHEIKHOLESLAMI, S. M.; BODAGHLI, A.; VOLKMANN, L. Twin signed Roman domination numbers in directed graphs. Tamkang Journal of Mathematics, [S. l.], v. 47, n. 3, p. 357-371, 2016. DOI: 10.5556/j.tkjm.47.2016.2035. Disponível em: https://journals.math.tku.edu.tw/index.php/TKJM/article/view/2035. Acesso em: 18 jan. 2022.