@article{MAN_1935__111_159761,
     author = {E.R. Neumann},
     title = {\"Uber die {Brennpunktsbedingungen} der {Variationsrechnung.}},
     journal = {Mathematische Annalen},
     pages = {83--93},
     publisher = {mathdoc},
     volume = {111},
     year = {1935},
     language = {de},
     url = {http://geodesic.mathdoc.fr/item/MAN_1935__111_159761/}
}