TY  - JOUR
AU  - S. A. Nazarov
TI  - Threshold resonances and virtual levels in the spectrum of~cylindrical and periodic waveguides
JO  - Izvestiya. Mathematics 
PY  - 2020
SP  - 1105
EP  - 1160
VL  - 84
IS  - 6
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/IM2_2020_84_6_a2/
LA  - en
ID  - IM2_2020_84_6_a2
ER  -