Dean Leffingwell, creator of SAFe®, is widely recognized as the one of the world's foremost authorities on Lean-Agile best practices. He is an author, serial entrepreneur, and software systems development methodologist. He is author of SAFe® 4.0 Reference Guide (Addison-Wesley, 2017). His two best-selling books, Agile Software Requirements: Lean Requirements Practices for Teams, Programs, and the Enterprise (Addison-Wesley, 2011), and Scaling Software Agility: Best Practices for Large Enterprises (Addison-Wesley, 2007), form much of the basis of modern thinking on Lean-Agile practices and principles.
Visit Dean's blog, on SAFe.