Fertig, M. The behavior of integrals of differential equations. (Romanian) Zbl 0227.34047 Stud. Univ. Babes-Bolyai, Ser. I 3, No. 3, 159-164 (1958). MSC: 34E10 PDFBibTeX XMLCite \textit{M. Fertig}, Stud. Univ. Babeș-Bolyai, Ser. Math.-Phys. 3, No. 3, 159--164 (1958; Zbl 0227.34047)
Hénon, Michel Un calcul amélioré des perturbations des vitesses stellaires (problème du ’Temps de Relaxation’). (French) Zbl 0112.46302 Ann. Astrophys. 21, 186-216 (1958). MSC: 85A05 PDFBibTeX XML Full Text: Link
Wintner, Aurel On linear perturbations. (English) Zbl 0080.06901 Q. Appl. Math. 15, 428-430 (1958). Reviewer: Lamberto Cesari MSC: 34-XX PDFBibTeX XMLCite \textit{A. Wintner}, Q. Appl. Math. 15, 428--430 (1958; Zbl 0080.06901) Full Text: DOI