@article{DAN_1968_179_4_a12,
     author = {F. I. Fedorov},
     title = {A first-order equation for the gravitational field},
     journal = {Doklady Akademii Nauk},
     pages = {802--805},
     year = {1968},
     volume = {179},
     number = {4},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1968_179_4_a12/}
}