@article{DAN_1972_204_4_a17,
     author = {Z. A. Steingrad},
     title = {Harmonic frames of reference in {Einstein's} theory of gravity},
     journal = {Doklady Akademii Nauk},
     pages = {831--833},
     publisher = {mathdoc},
     volume = {204},
     number = {4},
     year = {1972},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1972_204_4_a17/}
}