TY  - JOUR
AU  - M. G. Gasymov
AU  - B. M. Levitan
TI  - On the sum of the differences of the eigenvalues of two singular Sturm--Liouville operators
JO  - Doklady Akademii Nauk
PY  - 1963
SP  - 1014
EP  - 1017
VL  - 151
IS  - 5
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/DAN_1963_151_5_a4/
LA  - ru
ID  - DAN_1963_151_5_a4
ER  -