1. I. G. Petrovskii, Lectures on the Theory of Ordinary Differential Equations [in Russian], Gostekhizdat, Moscow-Leningrad (1952).
2. G. M. Fikhtenhol'tz, A Course in Differential and Integral Calculus [in Russian], Nauka, Moscow (1966).
3. Ya. D. Mamedov, One-Sided Estimates in Conditions in the Study of Solutions of Differential Equations in Banach Spaces, Élm, Baku (1971).
4. Z. B. Seidov, ?Boundary problems with parameter for differential equations in a Banach space,? Sib. Mat. Zh.,9, No. 1, 223?228 (1968).