@article{DAN_1980_250_3_a24,
     author = {A. I. Popykin},
     title = {Spectral properties of the stationary diffusion multigroup approximation},
     journal = {Doklady Akademii Nauk},
     pages = {607--610},
     publisher = {mathdoc},
     volume = {250},
     number = {3},
     year = {1980},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1980_250_3_a24/}
}