1. Ordinary Differential Equations;Hartman,1970
2. Asymptotic Properties of Solutions of Nonautonomous Ordinary Differential Equations;Kiguradze,1993
3. Equazioni differentiali nel campo reale II;Sansone,1949
4. Nonoscillation of solution of the equation x(n)+pn−1(t)x(n−1)+⋯+p0(t)x=0;Levin;Uspehi Mathematicheskih Nauk,1969
5. Theorem about differential inequality for multipoint boundary value problems;Chichkin;Izvestiya Vysshikh Uchebnykh Zavedeniĭ. Matematica,1962