@article{PMF_1923-1924_33_1_a7,
     author = {Witwi\'nski, Romuald},
     title = {La g\'eom\'etrie de direction},
     journal = {Prace Matematyczno-Fizyczne},
     pages = {99--114},
     publisher = {mathdoc},
     volume = {33},
     number = {1},
     year = {1923-1924},
     language = {fr},
     url = {http://geodesic.mathdoc.fr/item/PMF_1923-1924_33_1_a7/}
}