- The camera never lies: electronic line calls in focus again as Zverev takes photo of ball mark Reuters
- Alex Zverev given warning after using phone to take photo of disputed ball mark in Madrid Open victory CNN
- Tennis star Alexander Zverev calls out automated line judging system The Verge
- Alexander Zverev wins amid controversy in Madrid Tennis.com
- Madrid Open: Alexander Zverev penalised after ball-mark photograph BBC