%0 Journal Article %A Nelis, Peter %T Schur and Projective Schur Groups of Number Rings %J Canadian journal of mathematics %D 1991 %P 540-558 %V 43 %N 3 %U http://geodesic.mathdoc.fr/articles/10.4153/CJM-1991-033-5/ %R 10.4153/CJM-1991-033-5 %F 10_4153_CJM_1991_033_5