@article{MZ_1952__57_169305,
     author = {Hanfried Lenz},
     title = {\"Uber  {Orthogonaltrajektorien.}},
     journal = {Mathematische Zeitschrift},
     pages = {46--64},
     publisher = {mathdoc},
     volume = {57},
     year = {1952},
     language = {de},
     url = {http://geodesic.mathdoc.fr/item/MZ_1952__57_169305/}
}