@article{RO_2017__51_4_1331_0,
     author = {Atapour, Maryam and Dehgardi, Nasrin and Volkmann, L.},
     title = {An introduction to the twin signed total $k$-domination numbers in directed graphs},
     journal = {RAIRO - Operations Research - Recherche Op\'erationnelle},
     pages = {1331--1343},
     publisher = {EDP-Sciences},
     volume = {51},
     number = {4},
     year = {2017},
     doi = {10.1051/ro/2017036},
     mrnumber = {3783948},
     zbl = {1393.05195},
     language = {en},
     url = {http://archive.numdam.org/articles/10.1051/ro/2017036/}
}