@article{MZM_1991_49_3_a22,
     author = {L. M. Luzhina},
     title = {Regularity of spectral problems with supplementary conditions at interior points},
     journal = {Matemati\v{c}eskie zametki},
     pages = {151--153},
     publisher = {mathdoc},
     volume = {49},
     number = {3},
     year = {1991},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1991_49_3_a22/}
}