@article{DAN_1979_245_1_a7,
     author = {A. Fraguela Collar},
     title = {On the perturbation of a polyharmonic operator by potentials with small supports},
     journal = {Doklady Akademii Nauk},
     pages = {34--36},
     publisher = {mathdoc},
     volume = {245},
     number = {1},
     year = {1979},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1979_245_1_a7/}
}