You can find this exercise on page 267 of the book Synergistic Golf.
Exercise Type: DB STRENGTH
Exercise Category: BALANCE, CLUB CONTROL - ACCURACY, POSTURE, RHYTHM - TIMING, SHOULDERS, STRENGTH
Start with 3-5-8lb weight in right hand in top swing position. Lower right elbows onto right hip, shift body weight to left, keeping hand with weight back. Repeat 20-30x.