Firstpost Explains: What is a Smart Ball – the 'ball with a microchip' – set to be used for first time in professional league? - Firstcricket News, Firstpost
Topspin Rate: What The 2019 Stats Tell Us - UBITENNIS
No Matter How You Slice It, a Stealthy Backhand Still Works - The New York Times
USING TRACKING TECHNOLOGY TO ESTIMATE BALL SPIN IN TENNIS | Semantic Scholar
PDF) Ball spin in the tennis serve: Spin rate and axis of rotation