@article{UZERU_1987_3_a0,
     author = {G. V. Virabyan and G. A. Sargsian},
     title = {On multiple completeness of eigen functions of differential operator bunch generated by general boundary conditions},
     journal = {Proceedings of the Yerevan State University. Physical and mathematical sciences},
     pages = {3--8},
     publisher = {mathdoc},
     number = {3},
     year = {1987},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/UZERU_1987_3_a0/}
}