Tunc, Cemil2025-05-102025-05-1020072304-79092304-7895https://hdl.handle.net/20.500.14720/17649In this paper, we obtain some sufficient conditions under which the zero solution of a certain third order non-linear ordinary vector differential equation is unstable. Our results include and improve some well-known results exist in the literature.eninfo:eu-repo/semantics/closedAccessNonlinear Differential Equations Of Third OrderInstabilityLyapunov'S MethodArticle