The second midterm will cover the content from Lecture 14 until Lecture 21. Please see the lecture notes here.
Except for lectures 14, 15 and 16, the content of all the other lectures is contained here (11 pages).
I do not recommend that you follow the book for this part of the course, as we did not follow it very close.

If you really want to take a rough look at the book, we covered some parts of Chapter 8, 13 and 14:

D’Angelo/West, Mathematical Thinking, Second Edition

To see which parts we have covered exactly, please see the lecture log of this course.

For exercises, I recommend the following:

– Pages 166 to 168 in Chapter 8
– Pages 268 to 270 in Chapter 13
– Pages 287 to 289 in Chapter 14