@article{10_4153_CMB_1990_068_7,
     author = {Brown, Leon},
     title = {Invertible {Elements} in the {Dirichlet} {Space}},
     journal = {Canadian mathematical bulletin},
     pages = {419--422},
     year = {1990},
     volume = {33},
     number = {4},
     doi = {10.4153/CMB-1990-068-7},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CMB-1990-068-7/}
}