@article{PIM_1966_N_S_06_20_a4,
     author = {Stanimir Fempl},
     title = {Eine {Eigenschaft} {Der} {Brachistochronen} {Im} {Wirbelfreien} {Felde}},
     journal = {Publications de l'Institut Math\'ematique},
     pages = {25 },
     publisher = {mathdoc},
     volume = {_N_S_06},
     number = {20},
     year = {1966},
     url = {http://geodesic.mathdoc.fr/item/PIM_1966_N_S_06_20_a4/}
}