@article{MZM_1980_28_1_a16,
     author = {A. M. Mukhamedov},
     title = {Almost-projective mappings of gravitational fields},
     journal = {Matemati\v{c}eskie zametki},
     pages = {131--137},
     publisher = {mathdoc},
     volume = {28},
     number = {1},
     year = {1980},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1980_28_1_a16/}
}