@article{KUMEM_1927_2_a2,
     author = {F. Engel},
     title = {Zur {Dreiecks-geometrie} der {Lobatschefskijschen} {Ebene}},
     journal = {In memoriam N. I. Lobatschevskii},
     pages = {13--16},
     publisher = {mathdoc},
     volume = {2},
     year = {1927},
     language = {de},
     url = {http://geodesic.mathdoc.fr/item/KUMEM_1927_2_a2/}
}