@article{PMF_1923-1924_33_1_a0,
     author = {Witwi\'nski, Romuald},
     title = {Sur la th\'eorie des singularit\'es des \'equations diff\'erentielles du premi\`ere ordre},
     journal = {Prace Matematyczno-Fizyczne},
     pages = {1--10},
     publisher = {mathdoc},
     volume = {33},
     number = {1},
     year = {1923-1924},
     language = {fr},
     url = {http://geodesic.mathdoc.fr/item/PMF_1923-1924_33_1_a0/}
}