@article{DAN_1987_297_4_a1,
     author = {A. G. Zarubin},
     title = {Investigation of the {Galerkin{\textendash}Petrov} projection procedure by the method of fractional powers},
     journal = {Doklady Akademii Nauk},
     pages = {780--784},
     year = {1987},
     volume = {297},
     number = {4},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1987_297_4_a1/}
}