A fairly basic book about retrospectives.

The main goal of the book is not to provide the user with tons of techniques and ideas but rather provide a starting point for teams willing to start having retrospectives.
Pat shares the basis for a retrospective along with his experiences.

Esther Derby's book provides a more structured and longer description about retrospectives but also contains fewer examples and "real" world problems one may face.

The book is a good read for those who are not used to run retrospectives and would like to start doing so in an enterprise environment where the culture is not yet established.