%0 Journal Article %A Zorzitto, Frank %T Purity And Copurity in Systems of Linear Transformations %J Canadian journal of mathematics %D 1976 %P 889-896 %V 28 %N 4 %U http://geodesic.mathdoc.fr/articles/10.4153/CJM-1976-086-7/ %R 10.4153/CJM-1976-086-7 %F 10_4153_CJM_1976_086_7