@article{INTG_1974_6_a11,
     author = {M. V. Dragnev},
     title = {A certain class of point mappings of $P_3$ into~$P_2$},
     journal = {Itogi Nauki i Tekhniki. Seriya Problemy Geometrii. Trudy Geometricheskogo Seminara},
     pages = {223--241},
     publisher = {mathdoc},
     volume = {6},
     year = {1974},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/INTG_1974_6_a11/}
}