34A06 Generalized ordinary differential equations (measure-differential equations, set-valued differential equations, etc.) 17

34A12 Initial value problems, existence, uniqueness, continuous dependence and continuation of solutions to ordinary differential equations 5738

34A25 Analytical theory of ordinary differential equations: series, transformations, transforms, operational calculus, etc. [See also 44-XX] 3802

34A45 Theoretical approximation of solutions to ordinary differential equations {For numerical analysis, see 65Lxx} 3666