2013 NFL rule changes include elimination of 'Tuck Rule', peel-back
When N.F.L. Zebras Chat With Lions and Giants and Bears - The New
Week 2 referee assignments – Football Zebras
Walt Coleman Leads Referees Assigned To Falcons-Seahawks
Week 13 – Football Zebras
Football Zebras - Analysis and commentary of the NFL's officials
Rule changes for new football season: Officials to crackdown on
Column: Officiating won't get any better – because it can't
Football Zebras - Analysis and commentary of the NFL's officials
Official (gridiron football) - Wikipedia
NFL's 1st Female Official, Sarah Thomas, Broke Barriers Simply by
NFL Rule Changes in 2013 - Cincy Jungle
Football Zebras - Analysis and commentary of the NFL's officials