@article{JRAM_1840__20_147085,
     author = {C. Gudermann},
     title = {Theorie der {Modular-Functionen} und der {Modular-Integrale.}},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {62--87},
     year = {1840},
     volume = {20},
     language = {de},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1840__20_147085/}
}