Ordinary differential equations

Arnold, Ordinary differential equations

Amman, Ordinary differential equations

Tenenbaum, Ordinary differential equations

Teschl, Ordinary differential equations and dynamical systems

Hirsch, Smale, Devaney: Differential equations, dynamical systems and an introduction to chaos

Hille, Ordinary differential equations in the complex domain

Encyclopedic

Polyanin and Zaitsev, Handbook of ordinary differential equations

Note: See also the introductory section of the page on dynamical systems.