Chapter 26
Differential equations with applications and historial notes, George F. Simmons. Second edition. 1971

26.1 Chapter 2, section 7, page 37
26.2 Chapter 2, section 8, page 41
26.3 Chapter 2, section 10, page 47
26.4 Chapter 2, section 11, page 49
26.5 Chapter 2, End of chapter, page 61