Keller, R. G. The essential self-adjointness of differential operators with positive coefficients. (English) Zbl 0403.35031 Proc. R. Soc. Edinb., Sect. A 82, 345-360 (1979). MSC: 35J30 35R20 47F05 PDFBibTeX XMLCite \textit{R. G. Keller}, Proc. R. Soc. Edinb., Sect. A, Math. 82, 345--360 (1979; Zbl 0403.35031) Full Text: DOI
Keller, R. G. The essential self-adjointness of differential operators. (English) Zbl 0403.35030 Proc. R. Soc. Edinb., Sect. A 82, 305-344 (1979). MSC: 35J30 35R20 47F05 PDFBibTeX XMLCite \textit{R. G. Keller}, Proc. R. Soc. Edinb., Sect. A, Math. 82, 305--344 (1979; Zbl 0403.35030) Full Text: DOI