TY - JOUR AU - S. P. Novikov TI - Two-dimensional Schr\"odinger operators in periodic fields JO - Itogi Nauki i Tekhniki. Seriya Sovremennye Problemy Matematiki. Noveishie Dostizheniya PY - 1983 SP - 3 EP - 32 VL - 23 PB - mathdoc UR - http://geodesic.mathdoc.fr/item/INTD_1983_23_a0/ LA - ru ID - INTD_1983_23_a0 ER -