@article{TMF_1988_77_1_a4,
     author = {G. B. Pivovarov and F. V. Tkachev},
     title = {Inversion of the $R$~operation and $\xi$~functional},
     journal = {Teoreti\v{c}eska\^a i matemati\v{c}eska\^a fizika},
     pages = {51--59},
     publisher = {mathdoc},
     volume = {77},
     number = {1},
     year = {1988},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TMF_1988_77_1_a4/}
}