@article{GDZPPN002256398, title = {Ueber Tripelsysteme}, journal = {Mathematische Annalen}, volume = {49}, year = {1897}, pages = {101-112}, language = {de}, url = {http://dml.mathdoc.fr/item/GDZPPN002256398} }
Heffter, Lothar. Ueber Tripelsysteme. Mathematische Annalen, Tome 49 (1897) pp. 101-112. http://gdmltest.u-ga.fr/item/GDZPPN002256398/