Lepin, A. Ya. Existence of solutions of boundary value problems for a second order equation. (Russian) Zbl 0715.34041 Differ. Uravn. 26, No. 10, 1729-1737 (1990). Reviewer: J.Jarník MSC: 34B15 PDFBibTeX XMLCite \textit{A. Ya. Lepin}, Differ. Uravn. 26, No. 10, 1729--1737 (1990; Zbl 0715.34041)
Filippov, A. F. On perturbations of linear systems with quasiperiodic coefficients. (Russian) Zbl 0712.34068 Differ. Uravn. 26, No. 8, 1343-1348 (1990). Reviewer: W.Müller MSC: 34D08 34A30 34D10 34C27 65J99 PDFBibTeX XMLCite \textit{A. F. Filippov}, Differ. Uravn. 26, No. 8, 1343--1348 (1990; Zbl 0712.34068)