@article{MZM_1977_22_6_a5,
     author = {A. M. Minkin},
     title = {Regularity of self-adjoint boundary conditions},
     journal = {Matemati\v{c}eskie zametki},
     pages = {835--846},
     publisher = {mathdoc},
     volume = {22},
     number = {6},
     year = {1977},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1977_22_6_a5/}
}