@article{TRSPY_1984_165_a15,
     author = {A. N. Tyurin},
     title = {Local and global invariants of a~four-dimensional {pseudo-Riemannian} manifold},
     journal = {Informatics and Automation},
     pages = {205--219},
     publisher = {mathdoc},
     volume = {165},
     year = {1984},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TRSPY_1984_165_a15/}
}