The Philadelphia Athletics Historical Society - A great organization that you can visit online and in person

1911 Athletics Wikipedia Page

Society for American Baseball Research

Retrosheet - "Retrosheet was founded in 1989 for the purpose of computerizing play-by-play accounts of as many pre-1984 major league games as possible."

Baseball-reference - The most addictive website ever

Fangraphs - The second most addictive website ever

The Baseball Biography Project - Learn the stories behind the players.

Twitter - Yes, god forgive me, I got a twitter account for this site.