On This Day: Lou Gehrig blasted four home runs

Lou Gehrig Major League debut 100th anniversary

Lou Gehrig came of age with a Hartford summer 100 years ago

May 2 in sports history: Streak finally ends for 'luckiest man

4 Home Runs in a Game: Every Occurrence in MLB History

1927 Lou Gehrig bat, Joe DiMaggio jersey highlight Heritage Winter Platinum Auction - Sports Collectors Digest

Eighty Years On, Lou Gehrig's Words Reverberate - The New York Times

MLB Players Who Hit 4 Home Runs in One Game, by Andrew Martin

Scooter Gennett Hits Four Home Runs, Joining an Exclusive Club - The New York Times