It is a comprehensive (really) book - AGILE PRACTICE GUIDE by Project Management Institute really helps you to understand the topic
Michele Matteo GarciaNew York
The concepts explained in AGILE PRACTICE GUIDE PDF book are not the simplest ones. But however, Project Management Institute is a higly-skilled in making such kind of material easy to understand and implement in practice.
Britney2002 London
Got a PDF Kindle cversion of AGILE PRACTICE GUIDE - I guess a hardcopy would be better. Project Management Institute is a top-level prefessional