@article{IVM_1978_8_a2,
     author = {F. S. Akhrarov and A. P. Norden},
     title = {Intrinsic geometry of analytic surfaces of a~space of nondegenerate null-pairs},
     journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika},
     pages = {19--30},
     publisher = {mathdoc},
     number = {8},
     year = {1978},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/IVM_1978_8_a2/}
}