One-Arm Pushup

One of my clients has a goal of re-achieving the one-arm pushup. So I've started to bury myself in tutorials so I can help him reach his goal. Here is where I started.

Beastskills One Arm Pushup Tutorial

and

World's Strongest Librarian's One Arm Pushup Tutorial

If there are others I need to consult, let me know in the comments!