@article{VSGTU_2007_2_a22,
     author = {A. S. Tsareva},
     title = {Sufficient condition of {Hilbertness} of some eigenfunctions systems of the second order differential operator},
     journal = {Journal of Samara State Technical University, Ser. Physical and Mathematical Sciences},
     pages = {158--161},
     publisher = {mathdoc},
     number = {2},
     year = {2007},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/VSGTU_2007_2_a22/}
}