@article{10_4153_CMB_1980_065_0,
     author = {Groenewald, N. J.},
     title = {Units of the {Group} {Ring}},
     journal = {Canadian mathematical bulletin},
     pages = {445--448},
     year = {1980},
     volume = {23},
     number = {4},
     doi = {10.4153/CMB-1980-065-0},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CMB-1980-065-0/}
}