@article{IVM_1981_4_a5,
     author = {P. I. Kovalev},
     title = {Operators in {Lobachevskii} space},
     journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika},
     pages = {29--33},
     publisher = {mathdoc},
     number = {4},
     year = {1981},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/IVM_1981_4_a5/}
}