@article{10_1017_S0017089500003797,
     author = {Stothers, W. W.},
     title = {Diagrams associated with subgroups of {Fuchsian} groups},
     journal = {Glasgow mathematical journal},
     pages = {103--114},
     year = {1979},
     volume = {20},
     number = {2},
     doi = {10.1017/S0017089500003797},
     url = {http://geodesic.mathdoc.fr/articles/10.1017/S0017089500003797/}
}