@article{DMGT_2013_33_4_a6,
     author = {Volkmann, Lutz},
     title = {Bounds on the {Signed} {2-Independence} {Number} in {Graphs}},
     journal = {Discussiones Mathematicae. Graph Theory},
     pages = {709--715},
     publisher = {mathdoc},
     volume = {33},
     number = {4},
     year = {2013},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/DMGT_2013_33_4_a6/}
}