@article{DAN_1973_210_3_a2,
     author = {V. B. Kudryavtsev},
     title = {On the functional system $\mathscr{P}_\Sigma$},
     journal = {Doklady Akademii Nauk},
     pages = {521--522},
     publisher = {mathdoc},
     volume = {210},
     number = {3},
     year = {1973},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1973_210_3_a2/}
}