@article{10_4153_CJM_1969_159_0,
     author = {Stephenson, W.},
     title = {Unique {Addition} {Rings}},
     journal = {Canadian journal of mathematics},
     pages = {1455--1461},
     year = {1969},
     volume = {21},
     number = {1},
     doi = {10.4153/CJM-1969-159-0},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CJM-1969-159-0/}
}