@article{MZ_1933__37_168453,
     author = {R. Irrgang},
     title = {Ein singul\"ares bewegungsinvariantes {Variationsproblem.}},
     journal = {Mathematische Zeitschrift},
     pages = {381--401},
     publisher = {mathdoc},
     volume = {37},
     year = {1933},
     zbl = {59.0503.04},
     url = {http://geodesic.mathdoc.fr/item/MZ_1933__37_168453/}
}