TY - JOUR AU - Stothers, W. W. TI - Subgroups of infinite index in the modular group III JO - Glasgow mathematical journal PY - 1981 SP - 119 EP - 131 VL - 22 IS - 2 UR - http://geodesic.mathdoc.fr/articles/10.1017/S0017089500004559/ DO - 10.1017/S0017089500004559 ID - 10_1017_S0017089500004559 ER -