Cohn, J. H. E. On the number of bound states in a central field of force. (English) Zbl 0152.08502 J. Lond. Math. Soc. 41, 474-478 (1966). PDFBibTeX XMLCite \textit{J. H. E. Cohn}, J. Lond. Math. Soc. 41, 474--478 (1966; Zbl 0152.08502) Full Text: DOI
Cohn, J. H. E. On the number of negative eigen-values of a singular boundary value problem. II. (English) Zbl 0145.32701 J. Lond. Math. Soc. 41, 469-473 (1966). PDFBibTeX XMLCite \textit{J. H. E. Cohn}, J. Lond. Math. Soc. 41, 469--473 (1966; Zbl 0145.32701) Full Text: DOI