@article{MZ_1974__140_172142,
     author = {Robert Sandling},
     title = {Group {Rings} of {Circle} and {Unit} {Groups.}},
     journal = {Mathematische Zeitschrift},
     pages = {195--202},
     publisher = {mathdoc},
     volume = {140},
     year = {1974},
     zbl = {0281.20004},
     url = {http://geodesic.mathdoc.fr/item/MZ_1974__140_172142/}
}