A. From Exercises 6.7 on page 503 of the Book: 1, 3, 6, 8, 9, 21a)
B. From Exercises 6.8 on page 510 of the Book: 1, 3, 23, 24, 31, 35, 42, 45, 49
C. From Exercises 6.9 on page 518 of the Book: 6, 7, 11, 26, 27, 29, 39, 40, 46, 51, 57, 64, 66, 75, 78
D. From Exercises 6.10 on page 525 of the Book: 1, 20, 21, 29, 35, 39, 45, 47, 54, 58