Improve Your Backgammon
Chris Bray Backgammon
Backgammon To Win is recommended for beginners and those wishing to deepen their understanding of backgammon theory.
The “Wind” books are collections of articles from the Independent. Each article is a problem discussed on one page, so you can read bite size.
The position of the day on the web site has shorter discussions.
Free lively discussion board at an advanced level
US Backgammon Federation
Not restricted to US citizens