Scrum and XP from the Trenches by Henrik Kniberg
This book aims to give you a head start by providing a detailed down-to-earth account of how one Swedish company implemented Scrum and XP with a team of approximately 40 people and how they continuously improved their process over a year's time. Under the leadership of Henrik Kniberg they experimented with different team sizes, different sprint lengths, different ways of defining "done", different formats for product backlogs and sprint backlogs, different testing strategies, different ways of doing demos, different ways of synchronizing multiple Scrum teams, etc. They also experimented with XP practices - different ways of doing continuous build, pair programming, test driven development, etc, and how to combine this with Scrum.