Chapter 23
Theory and solutions of Ordinary Differential equations, Donald Greenspan, 1960

23.1 Chapter 2. First order equations. Exercises at page 14
23.2 Chapter 3. Linear differential equations of second order. Exercises at page 31
23.3 Chapter 4. The general linear differential equation of order n. Exercises at page 63
23.4 Chapter 6. Linear systems. Exercises at page 110
23.5 Chapter 7. Special functions. Exercises at page 124