Hofman, David Lower bounds on the first eigenvalue of the Laplacian of Riemannian submanifolds. (English) Zbl 0433.58019 Minimal submanifolds and geodesics, Proc. Jap.-U.S. Semin., Tokyo 1977, 61-72 (1979). MSC: 58J50 35K05 35P15 49Q05 53A10 PDFBibTeX XML
Fomenko, V. T. Some properties of two-dimensional surfaces with zero normal torsion in \(E^4\). (English) Zbl 0424.53005 Math. USSR, Sb. 35, 251-265 (1979). MSC: 53A05 PDFBibTeX XMLCite \textit{V. T. Fomenko}, Math. USSR, Sb. 35, 251--265 (1979; Zbl 0424.53005) Full Text: DOI