%0 Journal Article %T Summer Seminar %J Canadian mathematical bulletin %D 1965 %P 151-158 %V 8 %N 1 %U http://geodesic.mathdoc.fr/articles/10.1017/S0008439500024619/ %R 10.1017/S0008439500024619 %F 10_1017_S0008439500024619