Strauss, A.; Yorke, J. A. Perturbing asymptotically stable differential equations. (English) Zbl 0169.11001 Bull. Am. Math. Soc. 74, 992-996 (1968). PDFBibTeX XMLCite \textit{A. Strauss} and \textit{J. A. Yorke}, Bull. Am. Math. Soc. 74, 992--996 (1968; Zbl 0169.11001) Full Text: DOI
Yorke, J. A. Extending Liapunov’s second method to non-Lipschitz Liapunov functions. (English) Zbl 0155.13702 Bull. Am. Math. Soc. 74, 322-325 (1968). PDFBibTeX XMLCite \textit{J. A. Yorke}, Bull. Am. Math. Soc. 74, 322--325 (1968; Zbl 0155.13702) Full Text: DOI