%0 Journal Article %A Tuomas Sorvali %T The boundary mapping induced by an isomorphism of covering groups %J Annales Fennici Mathematici %D 1973 %V 521-560 %I mathdoc %U http://geodesic.mathdoc.fr/articles/10.5186/aasfm.1973.526/ %R 10.5186/aasfm.1973.526 %G en %F AFM_1973_521-560_a34