Rofe-Beketov, F. S. A test for the finiteness of the number of discrete levels introduced into the gaps of a continuous spectrum by perturbations of a periodic potential. (English. Russian original) Zbl 0117.06004 Sov. Math., Dokl. 5, 689-692 (1964); translation from Dokl. Akad. Nauk SSSR 156, 515-518 (1964). Page: −5 −4 −3 −2 −1 ±0 +1 +2 +3 +4 +5 Show Scanned Page Cited in 15 Documents Keywords:ordinary differential equations PDF BibTeX XML Cite \textit{F. S. Rofe-Beketov}, Sov. Math., Dokl. 5, 689--692 (1964; Zbl 0117.06004); translation from Dokl. Akad. Nauk SSSR 156, 515--518 (1964) OpenURL