@article{GDZPPN002089432, title = {The Group of Automorphisms of the Modular Function Field.}, journal = {Inventiones mathematicae}, volume = {14}, year = {1971}, pages = {253-254}, zbl = {0219.14018}, url = {http://dml.mathdoc.fr/item/GDZPPN002089432} }
Lang, Serge. The Group of Automorphisms of the Modular Function Field.. Inventiones mathematicae, Tome 14 (1971) pp. 253-254. http://gdmltest.u-ga.fr/item/GDZPPN002089432/