@article{MAN_1891__39_157580,
     author = {Fr. Schilling},
     title = {Ueber die geometrische {Bedeutung} der {Formeln} der sph\"arischen {Trigonometrie} im {Falle} complexer {Argumente}},
     journal = {Mathematische Annalen},
     pages = {598--600},
     publisher = {mathdoc},
     volume = {39},
     year = {1891},
     zbl = {23.0609.01},
     url = {http://geodesic.mathdoc.fr/item/MAN_1891__39_157580/}
}