- Galen, Bob. The Three Pillars of Agile Quality and Testing: Achieving Balanced Results in Your Journey Towards Agile Quality . Robert Galen and RGCG, LLC. http://rgalen.com/s/The-3-Pillars-of-Agile-Quality-and-Testing-BOOKv3.pdf.
- Cohn, Michael. Succeeding with Agile: Software Development Using Scrum . Boston: Addison Wesley, 2010.