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2. Asymptotic Behaviour and Stability Problems in Ordinary Differential Equations.;Cesari,1959
3. Discontinuous Automatic Control;Flügge-Lotz,1953
4. Theorie und Anwendung der direkten Methode von Liapunov;Hahn,1959
5. Über die Stabilität bei nichtlinearen Systemen;Hahn;Z. angew. Math. Mech.,1955