@article{DMGT_2019_39_1_a1,
     author = {Chen, Xiaodan and Hao, Guoliang and Xie, Zhihong},
     title = {A {Note} on {Roman} {Domination} of {Digraphs}},
     journal = {Discussiones Mathematicae. Graph Theory},
     pages = {13--21},
     publisher = {mathdoc},
     volume = {39},
     number = {1},
     year = {2019},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/DMGT_2019_39_1_a1/}
}