The "Roberta Sez" Series for Bridge is a treat for all learners! 
They are simple, concise, and throrough.  Each topic is explained well, with visual examples, and there is a quiz to test yourself on the topic, too.  
This book includes a Quick View Card that explains a few advanced conventions.
 
This book is for INTERMEDIATES: It includes topics on 2/1 Game Force system, 1NT Forcing, Cuebid Raises, Cuebid Stayman and more.
 
Suggestions:  Add on and get the 2/1  Bridge Guide Cheat Sheet with this book!