@article{VMUMM_1989_4_a4,
     author = {E. P. Bogomolova and A. S. Pechentsov},
     title = {Basic properties of the system of eigenfunctions of a boundary value problem with a multiple root of the characteristic polynomial},
     journal = {Vestnik Moskovskogo universiteta. Matematika, mehanika},
     pages = {17--22},
     publisher = {mathdoc},
     number = {4},
     year = {1989},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/VMUMM_1989_4_a4/}
}