Butuzov, V. F.; Kostin, A. V. On a singularly perturbed system of two second-order equations in the case of intersecting roots of the degenerate equation. (English. Russian original) Zbl 1190.34016 Differ. Equ. 45, No. 7, 933-950 (2009); translation from Differ. Uravn. 45, No. 7, 915-931 (2009). Reviewer: Galina Bizhanova (Almaty) MSC: 34B15 34E15 34E05 PDFBibTeX XMLCite \textit{V. F. Butuzov} and \textit{A. V. Kostin}, Differ. Equ. 45, No. 7, 933--950 (2009; Zbl 1190.34016); translation from Differ. Uravn. 45, No. 7, 915--931 (2009) Full Text: DOI
Kostin, A. V.; Shchegolev, S. A. On the stability of oscillations representable by Fourier series with slowly varying parameters. (English. Russian original) Zbl 1162.34303 Differ. Equ. 44, No. 1, 47-53 (2008); translation from Differ. Uravn. 44, No. 1, 45-51 (2008). MSC: 34A25 34D20 PDFBibTeX XMLCite \textit{A. V. Kostin} and \textit{S. A. Shchegolev}, Differ. Equ. 44, No. 1, 47--53 (2008; Zbl 1162.34303); translation from Differ. Uravn. 44, No. 1, 45--51 (2008) Full Text: DOI
Kostin, A. V. Generalized Stepanov spaces and evolution equations. (English. Russian original) Zbl 1082.34530 Differ. Equ. 39, No. 3, 457-459 (2003); translation from Differ. Uravn. 39, No. 3, 421-422 (2003). MSC: 34G10 26A33 46E99 PDFBibTeX XMLCite \textit{A. V. Kostin}, Differ. Equ. 39, No. 3, 457--459 (2003; Zbl 1082.34530); translation from Differ. Uravn. 39, No. 3, 421--422 (2003) Full Text: DOI