Reading of the reference book is not required. Students that are willing to do so may read: 

- Chapter 9.1
- Chapter 9.2

Note:

Chapter 9.2: 

1. The textbook's proof "Derivation of (2) from (1)" on Page 363 is wrong! 

2. Ex 2 and 3 are good but you may get confused if you are not confident about physics. 

Chapter 9.3: 

1. Again you may ignore Ex 3, 4 and 5 if you are not confident about physics.