@article{DAN_1972_206_2_a8,
     author = {V. A. Sadovnichii},
     title = {Uniqueness of the solution to the inverse problem in the case of a second-order equation with indecomposable boundary conditions. {Regularized} sums of some of the eigenvalues. {Factorization} of the characteristic determinant},
     journal = {Doklady Akademii Nauk},
     pages = {293--296},
     publisher = {mathdoc},
     volume = {206},
     number = {2},
     year = {1972},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1972_206_2_a8/}
}