@article{10_4153_CJM_1973_024_8,
     author = {Hell, Pavol and Ne\v{s}et\v{r}il, Jaroslav},
     title = {Groups and {Monoids} of {Regular} {Graphs} {(And} of {Graphs} with {Bounded} {Degrees)}},
     journal = {Canadian journal of mathematics},
     pages = {239--251},
     year = {1973},
     volume = {25},
     number = {2},
     doi = {10.4153/CJM-1973-024-8},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CJM-1973-024-8/}
}