Il’in, V. A.; Filippov, A. F. The nature of the spectrum of a selfadjoint extension of the Laplace operator in a bounded region (fundamental systems of functions with an arbitrary preassigned subsequence of fundamental numbers). (English. Russian original) Zbl 0209.41302 Sov. Math., Dokl. 11, 339-342 (1970); translation from Dokl. Akad. Nauk SSSR 191, 267-269 (1970). Page: −5 −4 −3 −2 −1 ±0 +1 +2 +3 +4 +5 Show Scanned Page Cited in 3 Documents MSC: 35P05 General topics in linear spectral theory for PDEs 35J05 Laplace operator, Helmholtz equation (reduced wave equation), Poisson equation 47A20 Dilations, extensions, compressions of linear operators PDFBibTeX XMLCite \textit{V. A. Il'in} and \textit{A. F. Filippov}, Sov. Math., Dokl. 11, 339--342 (1970; Zbl 0209.41302); translation from Dokl. Akad. Nauk SSSR 191, 267--269 (1970)