What are you reading on your smartphone, tablet, or Kindle?

You will find some suggestions in the Teach Yourself Guides page, but my suggestion is:

• Partnership Bidding at Bridge (PDF) by Robson/Segal - the best book on partnership competitive bidding, although it is complex and best for established partnerships. You may not play everything they suggest, but it will make you think.

Even if you are not in a regular partnership, reading this book will improve your game.