TY  - JOUR
TI  - P 13.
JO  - Canadian mathematical bulletin
PY  - 1959
SP  - 43
EP  - 43
VL  - 2
IS  - 1
UR  - http://geodesic.mathdoc.fr/articles/10.1017/S0008439500024887/
DO  - 10.1017/S0008439500024887
ID  - 10_1017_S0008439500024887
ER  -