TY  - JOUR
AU  - Cohen, Jeffrey
TI  - On non-Hurwitz groups and non-congruence subgroups of the modular group
JO  - Glasgow mathematical journal
PY  - 1981
SP  - 1
EP  - 7
VL  - 22
IS  - 1
UR  - http://geodesic.mathdoc.fr/articles/10.1017/S0017089500004419/
DO  - 10.1017/S0017089500004419
ID  - 10_1017_S0017089500004419
ER  -