69.1 Section 1. Basic concepts and definitions. Exercises page 18

69.1.1 problem 2
69.1.2 problem 3
69.1.3 problem 4
69.1.4 problem 5
69.1.5 problem 6
69.1.6 problem 7
69.1.7 problem 8
69.1.8 problem 9
69.1.9 problem 10
69.1.10 problem 11
69.1.11 problem 13
69.1.12 problem 14
69.1.13 problem 15
69.1.14 problem 16