Atlantic League introduces 'robot umpires' to baseball - The Washington Post
Baseball umpire : Career Outlook: U.S. Bureau of Labor Statistics
MLB umpire Joe West has never missed a call. Just ask him - ESPN
Robot umpire: Baseball edges closer to implementing automatic strike zone in major leagues
Umpire (baseball) - Wikipedia
Commentary: Major-league ump Ed Rapuano backs Pope John Paul II
Umpire (baseball) - Wikipedia
Baseball Umpires
MLB umpire job responsibilities
Does MLB Have an Umpire Problem Sports Analytics Group at Berkeley
Beyond the Strike Zone: Exploring the Vital Role of Umpires in a Game - Ump Junk - Officials Gear
The MLB Umpires Association is a flawed and opaque organization - Bleed Cubbie Blue
If you aren't a white male, YER OUT of luck as an umpire - Global Sport Matters