Chapter 18
Mathematical methods for physics and engineering, Riley, Hobson, Bence, second edition, 2002

18.1 Chapter 14, First order ordinary differential equations. 14.4 Exercises, page 490
18.2 Chapter 15, Higher order ordinary differential equations. 15.4 Exercises, page 523
18.3 Chapter 16, Series solutions of ODEs. Section 16.6 Exercises, page 550