@article{DMGT_2018_38_4_a0,
     author = {Besson, Marc and Tesman, Barry},
     title = {T\protect\textsubscript{r} {-Span} of {Directed} {Wheel} {Graphs}},
     journal = {Discussiones Mathematicae. Graph Theory},
     pages = {871--888},
     publisher = {mathdoc},
     volume = {38},
     number = {4},
     year = {2018},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/DMGT_2018_38_4_a0/}
}