1. Chapter 1
   1. Section 1
      1. Topic 1
      2. Topic 2
   2. Section 2
      1. Topic 1
      2. Topic 2
      3. Topic 3
2. Chapter 2
3. Chapter 3
   1. Section 1
      1. Topic 1
   2. Section 2
   3. Section 3
      1. Topic 1
      2. Topic 2
4. Chapter 4
   1. Section 1
   2. Section 2
   3. Section 3