BOOK: SBOK Guide - A Guide to the SCRUM BODY OF KNOWLEDGE

One interesting thorough book on Scrum, talking of Scrum of Scrums and many other interesting topics is the SBOK™ Guide (A Guide to the SCRUM BODY OF KNOWLEDGE).
The PDF links are:

• www.scrumstudy.com/download-free-SBOK.asp (English version)
• www.scrumstudy.com/download-free-SBOK.asp?lan=pt ("Portuguese" version)