Scrum Definitive Guide | Scrum.org (Agile)

This is the link to "The Definitive Guide to Scrum" (developed and sustained by Ken Schwaber and Jeff Sutherland, scrum.org, and also known as Scrum Official Guide or SOG), 16 pages that changed the way we produce (some) software:

• http://www.scrumguides.org/docs/scrumguide/v1/scrum-guide-us.pdf: July 2013 version; older versions include May 2009 and October 2011. PS. In 2016 a new version of the guide was provided by the authors.
• The 2017 version is here: http://www.scrumguides.org/docs/scrumguide/v2017/2017-Scrum-Guide-US.pdf#zoom=100 and can be browsed online here: http://www.scrumguides.org/index.html
• In PT BR: http://www.scrumguides.org/docs/scrumguide/v1/Scrum-Guide-Portuguese-BR.pdf

(@2016-06-08: Added aka; 2016-10-17: added PS; 2018-02-21: rephrased, added link to V2017; added link to PT BR version)