History of retired numbers dates back to Lou Gehrig Day

Lou Gehrig - Wikipedia

Lou Gehrig's disease: Why ALS is forever associated with one of America's baseball greats

Gehrig's farewell speech still echoes in baseball, Professional sports

America's Tragic Hero: The Yankees's Lou Gehrig

History of retired numbers dates back to Lou Gehrig Day

Retired Number Series: Cincinnatti Reds The Harvard Sports Analysis Collective

New York Yankees Retired Numbers - Sports Illustrated

Mets retire Willie Mays' No. 24 as Old-Timers' Day returns

The forgotten history of baseball players' numbers – Cranberry Eagle

Rangers set to make Pudge's No. 7 their third retired number; who should be next, plus a historical look

Last Ride of the Iron Horse – Sunbury Press Bookstore

Yankees Fourth of July memories: Lou Gehrig's 'Luckiest Man' Speech, Bronx Pinstripes