@article{DAN_1989_304_4_a11,
     author = {V. I. Zubov},
     title = {Pencils of kinematic trajectories},
     journal = {Doklady Akademii Nauk},
     pages = {817--819},
     publisher = {mathdoc},
     volume = {304},
     number = {4},
     year = {1989},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1989_304_4_a11/}
}