@article{MAN_1977__228_162996,
     author = {A.P. Ogg},
     title = {\"Uber die {Automorphismengruppe} von {X0(N).}},
     journal = {Mathematische Annalen},
     pages = {279--292},
     publisher = {mathdoc},
     volume = {228},
     year = {1977},
     zbl = {0336.14002},
     url = {http://geodesic.mathdoc.fr/item/MAN_1977__228_162996/}
}