@article{PMF_1949_47_1_a9,
     author = {Biernacki, M.},
     title = {Sur un th\'eor\`eme dans la th\'eorie des \'equations diff\'erentielles},
     journal = {Prace Matematyczno-Fizyczne},
     pages = {129--141},
     publisher = {mathdoc},
     volume = {47},
     number = {1},
     year = {1949},
     language = {fr},
     url = {http://geodesic.mathdoc.fr/item/PMF_1949_47_1_a9/}
}