Elbert, Árpád; Kusano, Takaŝi Principal solutions of non-oscillatory half-linear differential equations. (English) Zbl 0914.34031 Adv. Math. Sci. Appl. 8, No. 2, 745-759 (1998). MSC: 34C10 PDF BibTeX XML Cite \textit{Á. Elbert} and \textit{T. Kusano}, Adv. Math. Sci. Appl. 8, No. 2, 745--759 (1998; Zbl 0914.34031) OpenURL
Zhu, Xiaodong A Sturm type comparison theorem for nonlinear problems. (English) Zbl 0862.34027 J. Differ. Equations 129, No. 1, 166-192 (1996). Reviewer: Charles A.Swanson (Vancouver) MSC: 34C10 35J65 PDF BibTeX XML Cite \textit{X. Zhu}, J. Differ. Equations 129, No. 1, 166--192 (1996; Zbl 0862.34027) Full Text: DOI Link OpenURL
Kreith, Kurt Picone-type theorems for hyperbolic partial differential equations. (English) Zbl 0458.35008 Pac. J. Math. 102, 385-395 (1982). MSC: 35B05 35L20 35A30 PDF BibTeX XML Cite \textit{K. Kreith}, Pac. J. Math. 102, 385--395 (1982; Zbl 0458.35008) Full Text: DOI OpenURL