81.13 Chapter 17. Reduction of Order. Page 420

81.13.1 problem 17-1
81.13.2 problem 17-2
81.13.3 problem 17-3
81.13.4 problem 17-4
81.13.5 problem 17-5
81.13.6 problem 17-6
81.13.7 problem 17-7
81.13.8 problem 17-8
81.13.9 problem 17-9
81.13.10 problem 17-10
81.13.11 problem 17-11