@article{10_4153_CJM_1976_049_3,
     author = {Fine, Benjamin},
     title = {Fuchsian {Subgroups} of the {Picard} {Group}},
     journal = {Canadian journal of mathematics},
     pages = {481--485},
     year = {1976},
     volume = {28},
     number = {3},
     doi = {10.4153/CJM-1976-049-3},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CJM-1976-049-3/}
}