Mustafin, M. A. On the Riesz basis of a sine system. (Russian) Zbl 0696.34013 Differ. Uravn. 25, No. 10, 1832-1833 (1989). Reviewer: N.Bozhinov MSC: 34B10 42C30 42C15 PDFBibTeX XMLCite \textit{M. A. Mustafin}, Differ. Uravn. 25, No. 10, 1832--1833 (1989; Zbl 0696.34013)
Budaev, V. D. On unconditional basis property on a closed interval of systems of eigen- and adjoint functions of a second order operator with discontinuous coefficients. (Russian) Zbl 0636.34017 Differ. Uravn. 23, No. 6, 941-952 (1987). Reviewer: B.Šehter MSC: 34L99 42C30 PDFBibTeX XMLCite \textit{V. D. Budaev}, Differ. Uravn. 23, No. 6, 941--952 (1987; Zbl 0636.34017)