Voir la notice de l'article provenant de la source European Digital Mathematics Library
@article{MAN_1897__49_157842, author = {Lothar Heffter}, title = {Ueber {Tripelsysteme}}, journal = {Mathematische Annalen}, pages = {101--112}, publisher = {mathdoc}, volume = {49}, year = {1897}, language = {de}, url = {http://geodesic.mathdoc.fr/item/MAN_1897__49_157842/} }
Lothar Heffter. Ueber Tripelsysteme. Mathematische Annalen, Tome 49 (1897), pp. 101-112. http://geodesic.mathdoc.fr/item/MAN_1897__49_157842/