TY  - JOUR
AU  - Cummins, C.J.
TI  - Congruence subgroups of groups commensurable with  of genus 0 and 1.
JO  - Experimental mathematics
PY  - 2004
SP  - 361
EP  - 382
VL  - 13
IS  - 3
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/EXMA_2004__13_3_52776/
LA  - en
ID  - EXMA_2004__13_3_52776
ER  -