@article{DE_1970_6_7_a1,
     author = {V. A. Il'in},
     title = {A generalized principle of localization for the {Riesz} means that correspond to an arbitrary selfadjoint nonnegative extension of the {Laplace} operator},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1159--1169},
     publisher = {mathdoc},
     volume = {6},
     number = {7},
     year = {1970},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1970_6_7_a1/}
}