@article{KUTGS_1975_8_a5,
     author = {M. V. Dragnev and V. V. Ryzhkov},
     title = {On the differential geometry of mappings of ruled projective spaces},
     journal = {Trudy Geometricheskogo Seminara},
     pages = {49--56},
     publisher = {mathdoc},
     volume = {8},
     year = {1975},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/KUTGS_1975_8_a5/}
}