You should not need to read this to do assignment 7. However it might be useful if you want to explore further.
Cornel K. Pokorny & Curtis F. Gerald, "Computer Graphics: The Principles behind the art and science", Franklin, Beedle & Associates, 1989. pp.403.
This book explains the Depth Sort algorithm in a step by step way. It also includes an algorithm to decompose a polygon into triangles.