TY  - JOUR
TI  - A Letter to Professor J. Lambek
JO  - Canadian mathematical bulletin
PY  - 1969
SP  - 382
EP  - 383
VL  - 12
IS  - 3
UR  - http://geodesic.mathdoc.fr/articles/10.1017/S0008439500030666/
DO  - 10.1017/S0008439500030666
ID  - 10_1017_S0008439500030666
ER  -