@article{RM_2005_60_1_a11,
     author = {S. A. Stepin and V. N. Titov},
     title = {On perturbation of a multiple eigenvalue},
     journal = {Trudy Matematicheskogo Instituta imeni V.A. Steklova},
     pages = {169--170},
     publisher = {mathdoc},
     volume = {60},
     number = {1},
     year = {2005},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/RM_2005_60_1_a11/}
}