@article{DMGT_2011_31_4_a5,
     author = {Volkmann, Lutz},
     title = {Connected global offensive k-alliances in graphs},
     journal = {Discussiones Mathematicae. Graph Theory},
     pages = {699--707},
     publisher = {mathdoc},
     volume = {31},
     number = {4},
     year = {2011},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/DMGT_2011_31_4_a5/}
}