@article{IVM_1986_4_a2,
     author = {A. I. Vahabov},
     title = {Conditions for multiple completeness of eigenelements of an ordinary differential pencil},
     journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika},
     pages = {13--20},
     publisher = {mathdoc},
     number = {4},
     year = {1986},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/IVM_1986_4_a2/}
}