Work or walk: Lackawanna League umpires demand more pay
Umpires – Zionsville Little League
Umpires
MLB umpire job responsibilities
10 Major League Baseball umpires retire in historic exodus
A Writer Enters The 'Land of Umpires' : NPR
Robot Umpires Could Be Coming to MLB as Soon as 2024 - CNET
Umpire Program
MLB umpires have a new signal to call this spring - Sports Illustrated