TY  - JOUR
AU  - Stothers, W. W.
TI  - Subgroups of infinite index in the modular group
JO  - Glasgow mathematical journal
PY  - 1978
SP  - 33
EP  - 43
VL  - 19
IS  - 1
UR  - http://geodesic.mathdoc.fr/articles/10.1017/S0017089500003347/
DO  - 10.1017/S0017089500003347
ID  - 10_1017_S0017089500003347
ER  -