Cowboys' Jayron Kearse no longer switching to No. 0 jersey
Uniform number (American football) - Wikipedia
Has Baker Mayfield already won Buccaneers starting job? - Bucs Nation
Squad number (association football) - Wikipedia
NFL's relaxed jersey rules: Meet the players who now wear No. 0
Why NFL players were drawn to jersey No. 0 after its return - ESPN
The complete history of signature shoes in the NFL
NFL rule proposal would allow more players to wear single-digit numbers like in college football
Why can't NFL players wear number 0? - Quora
NFL jersey number updates: Tracking which NFL players wear No. 0 - ESPN