@article{VYURU_2011_9_a1,
     author = {S. I. Kadchenko and S. N. Kakushkin},
     title = {The first four corrections of the perturbation theory for discrete semi bounded from below operators with free multiplicities of eigenvalues finding},
     journal = {Vestnik \^U\v{z}no-Uralʹskogo gosudarstvennogo universiteta. Seri\^a, Matemati\v{c}eskoe modelirovanie i programmirovanie},
     pages = {16--21},
     publisher = {mathdoc},
     number = {9},
     year = {2011},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/VYURU_2011_9_a1/}
}