%0 Journal Article %T On the group ring of a free product with amalgamation %J Glasgow mathematical journal %D 1980 %P 135-138 %V 21 %N 2 %U http://geodesic.mathdoc.fr/articles/10.1017/S0017089500004274/ %R 10.1017/S0017089500004274 %F 10_1017_S0017089500004274