Amazon.com : PENDULUM PRO Golf Swing Trainer - 3 in 1 Golf Training Aid - Chipping, Putting, & Initial Take Away Trainer - Instant Feedback to Improve Golf Game : Sports & Outdoors
Clement: Golf's pendulum chaos theory – GolfWRX
North South Pendulum Golf Swing by Lee Adger – African American Golfer's Digest
Amazon.com : PENDULUM PRO Golf Swing Trainer - 3 in 1 Golf Training Aid - Chipping, Putting, & Initial Take Away Trainer - Instant Feedback to Improve Golf Game : Sports & Outdoors