@article{JRAM_1830__6_146707,
     author = {C. Gudermann},
     title = {\"Uber die analytische {Sph\"arik.}},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {244--254},
     year = {1830},
     volume = {6},
     language = {de},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1830__6_146707/}
}