The Lethal Closed Guard by Rudson Mateus

Good techniques. Doesn’t try to over complicate things or make out they are more ground breaking than they are - just solid, effective techniques.

Everything you need to know in order to develop a really strong closed guard clearly explained.

Advanced Fundamentals

This is a solid collection of overlooked closed guard fundamentals. Rudson teaches them well, and they should be in everyone's repertoire.