@article{10_1017_S0017089514000202,
     author = {KIRSCHMER, MARKUS and LEEDHAM-GREEN, CHARLES},
     title = {COMPUTING {WITH} {SUBGROUPS} {OF} {THE} {MODULAR} {GROUP}},
     journal = {Glasgow mathematical journal},
     pages = {173--180},
     year = {2015},
     volume = {57},
     number = {1},
     doi = {10.1017/S0017089514000202},
     url = {http://geodesic.mathdoc.fr/articles/10.1017/S0017089514000202/}
}