@article{TRSPY_1990_192_a4,
     author = {Yu. D. Golovatyj and S. A. Nazarov and O. A. Oleinik},
     title = {Asymptotic expansions of eigenvalues and eigenfunctions in problems on oscillations of a~medium with concentrated perturbations},
     journal = {Informatics and Automation},
     pages = {42--60},
     publisher = {mathdoc},
     volume = {192},
     year = {1990},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TRSPY_1990_192_a4/}
}