@article{DMGT_2010_30_4_a4,
     author = {Hammack, Richard and Toman, Katherine},
     title = {Cancellation of direct products of digraphs},
     journal = {Discussiones Mathematicae. Graph Theory},
     pages = {575--590},
     publisher = {mathdoc},
     volume = {30},
     number = {4},
     year = {2010},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/DMGT_2010_30_4_a4/}
}