REBOL Books

REBOL is a niche language.  It seems that publishers are not willing to take the risk of printing books on the topic when there is such a small potential audience.  I have REBOL: The Official Guide, with a foreword by Carl Sassenrath (the creator of REBOL).  It is an older book, copyright © 2000.  Another book is Rebol Programmation, which is written in French and copyright © 2001.  A recent follow-up (also in French) is REBOL Guide du programmeur.

One thing that will be helpful is to write books and guides and export them to PDF.  It is necessary to ensure that they are consistently well-written, attractively formatted, and accurate.  Because of possible differences between versions, any such tutorials should be clearly marked, "covers version 2.3 to 2.5" or whatever is accurate.

An existing PDF tutorial is REBOL Essentials. [PDF]

There is said to be one other REBOL book, but I have not seen it or heard of it.  Of course, it could be one of those on the Amazon page.