If you haven't checked out Master Pedro Sauer's book "Mastering the Closed Guard and It's Submissions" you're really missing out. This book, written in combination with me :) , is a masterpiece and a must for anyone serious about their GJJ game. Passing the guard is a cornerstone of Jiu-Jitsu and Pedro goes into the details that truly make a difference in anyone's game
Master Pedro Sauer is a direct disciple of the creator of Gracie Jiu-Jitsu Grandmaster Helio Gracie. His experience and technical knowledge are considered to be some of the finest in the World. Is his first book Master Sauer dissects one of the most important and difficult tasks in Gracie Jiu-Jitsu, to overcome the defensive barrier of the "Guard". But Master Sauer goes beyond just defeating the "guard" and advances into series of submissions that will be invaluable to anyone practicing the art of Gracie
Available in printed and e-book versions. Check it out at : http://bjjmart.com/loja.asp