@article{DAN_1987_297_5_a5,
     author = {G. I. Olshanskii},
     title = {Extension of the algebra $\mathscr{U}(\mathfrak{g})$ for infinite-dimensional classical {Lie} algebras $\mathfrak{g}$ and},
     journal = {Doklady Akademii Nauk},
     pages = {1050--1054},
     year = {1987},
     volume = {297},
     number = {5},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1987_297_5_a5/}
}