TY  - JOUR
AU  - N. V. Assonova
AU  - V. D. Budaev
TI  - The Hilbert and Bessel properties of systems of eigenfunctions of second-order operators
JO  - Differencialʹnye uravneniâ
PY  - 2000
SP  - 147
EP  - 151
VL  - 36
IS  - 2
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/DE_2000_36_2_a0/
LA  - ru
ID  - DE_2000_36_2_a0
ER  -