Chapter 80
Elementary Differential Equations. By Thornton C. Fry. D Van Nostrand. NY. First Edition (1929)

80.1 Chapter 1. section 5. Problems at page 19
80.2 Chapter IV. Methods of solution: First order equations. section 24. Problems at page 62
80.3 Chapter IV. Methods of solution: First order equations. section 29. Problems at page 81
80.4 Chapter IV. Methods of solution: First order equations. section 31. Problems at page 85
80.5 Chapter IV. Methods of solution: First order equations. section 32. Problems at page 89
80.6 Chapter IV. Methods of solution: First order equations. section 33. Problems at page 91
80.7 Chapter V. Singular solutions. section 36. Problems at page 99
80.8 Chapter VII. Linear equations of order higher than the first. section 56. Problems at page 163
80.9 Chapter VII. Linear equations of order higher than the first. section 63. Problems at page 196