@article{10_4153_CJM_1977_014_3,
     author = {Fine, Benjamin},
     title = {Sum of {Squares} {Rings}},
     journal = {Canadian journal of mathematics},
     pages = {155--160},
     year = {1977},
     volume = {29},
     number = {1},
     doi = {10.4153/CJM-1977-014-3},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CJM-1977-014-3/}
}