Commentary: Tennis technology erases John McEnroe-esque fun - Los Angeles Times
What Is A Tennis Line Judge?
Officiating in Tennis | ITF
Officials at a tennis match
Serena Williams' U.S. Open penalties spark debate over sexism in sports
Worst line calls and umpire decisions in Tennis - YouTube
5,279 Tennis Referee Photos and Premium High Res Pictures - Getty Images
Tennis Referee Chair Umpire Stock Photos - Free & Royalty-Free Stock Photos from Dreamstime
Tennis umpire hi-res stock photography and images - Alamy
Kader Nouni: The Umpire Known as the 'Barry White of Tennis' - The New York Times
Umpires Hand Signals
Serena Williams had crazy outburst at US Open after calling umpire "liar" and "thief" - Mirror Online
Umpires Hand Signals
Serena Williams calls out sexism in tennis | The Chatterbox
Roles of Officials - Tennis Canada
The U.S Open replaces human line judges with optical technology : NPR
Official (tennis) - Wikipedia
Tennis scoring, rules and officials - Tennis - factfile - GCSE Physical Education Revision - Edexcel - BBC Bitesize
What Is An Umpire In Tennis?
Softball terminology and referee signals
Merlin | Philosophy Referee Hand Signals
Official (tennis) - Wikipedia
8 Umpire Hand Signals You Need to Know - PingSunday
