@article{INTG_1969_2_a9,
     author = {N. M. Ostianu},
     title = {Certain projective differential structures on a~differentiable manifold},
     journal = {Itogi Nauki i Tekhniki. Seriya Problemy Geometrii. Trudy Geometricheskogo Seminara},
     pages = {207--246},
     publisher = {mathdoc},
     volume = {2},
     year = {1969},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/INTG_1969_2_a9/}
}