@article{MAN_1975__218_162785,
     author = {Dan Kubert and Serge Lang},
     title = {Units in the {Modular} {Function} {Field.} {I.}},
     journal = {Mathematische Annalen},
     pages = {67--96},
     publisher = {mathdoc},
     volume = {218},
     year = {1975},
     zbl = {0311.14005},
     url = {http://geodesic.mathdoc.fr/item/MAN_1975__218_162785/}
}