81.12 Chapter 16. Variation of Parameters. Page 375.

81.12.1 problem 16-1
81.12.2 problem 16-2
81.12.3 problem 16-3
81.12.4 problem 16-4
81.12.5 problem 16-5 and 16-7
81.12.6 problem 16-6
81.12.7 problem 16-8
81.12.8 problem 16-9
81.12.9 problem 16-10
81.12.10 problem 16-11
81.12.11 problem 16-12
81.12.12 problem 16-13
81.12.13 problem 16-14
81.12.14 problem 16-15
81.12.15 problem 16-16
81.12.16 problem 16-17
81.12.17 problem 16-18
81.12.18 problem 16-19
81.12.19 problem 16-20
81.12.20 problem 16-21
81.12.21 problem 16-22