@article{10_4153_CJM_1969_009_1,
     author = {Barnes, Bruce Alan},
     title = {The {Fredholm} {Elements} of a {Ring}},
     journal = {Canadian journal of mathematics},
     pages = {84--95},
     year = {1969},
     volume = {21},
     number = {1},
     doi = {10.4153/CJM-1969-009-1},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CJM-1969-009-1/}
}