Articles and information I found interesting.
Traditional Swing versus Kickback Swing: Which is Best? (Florida Baseball Armory)
How To Turn Fastpitch Softball Hitting Mechanics Into A High Level Baseball Swing…Can It Be Done? (Hitting Performance Lab)
Overload and Underload Bat Training
How to Increase Your Bat Speed (Driveline)
Underload Overload Bats – Weighted Bat Training (Bat Digest)
Swinging a Weighted Bat On-Deck
Tip for Casey: To Swing a Faster Bat, Lighten Up That Lumber (Scientific American)