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2. On the existence of a limiting regime of a certain non-linear system of ordinary differential equations;Demidovic;Amer. Math. Soc. Transl.,1961
3. A generalization of a result of Demidovic on the existence of a limiting regime of a system of differential equations;Ezeilo;Portugal. Math.,1965
4. New properties of the equation ⋯x + aẍ + bẋ + h(x) = p(t, x, ẋ, ẍ) for certail sp y−1 {h(x − y) − h(x)};Ezeilo,1973
5. Non-linear Differential Equations of Higher Order;Reissig,1974