@article{DMGT_2017_37_1_a18,
     author = {Volkmann, Lutz},
     title = {Signed {Total} {Roman} {Domination} in {Digraphs}},
     journal = {Discussiones Mathematicae. Graph Theory},
     pages = {261--272},
     publisher = {mathdoc},
     volume = {37},
     number = {1},
     year = {2017},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/DMGT_2017_37_1_a18/}
}