@article{PMF_1937_44_1_a0,
     author = {Hadamard, J.},
     title = {Probl\`eme topologique sur les \'equations diff\'erentielles},
     journal = {Prace Matematyczno-Fizyczne},
     pages = {1--7},
     publisher = {mathdoc},
     volume = {44},
     number = {1},
     year = {1937},
     language = {fr},
     url = {http://geodesic.mathdoc.fr/item/PMF_1937_44_1_a0/}
}