Re: Birthdays: 2/20
During the week I do these at work so I mostly rely on Baseballreference.com, Wikipedia and whatever articles Wikipedia links me to. On weekends I do them at home, so I have access to some additional stuff: The Bill James Historical Abstract, the Dickson book of baseball quotes, the Neyer/James book of pitchers, and of course the indispensible Great American Baseball Card Book by Boyd and Harris, which everyone should own.
The best is when Baseballreference has a link to a SABR bio of a player.
"In baseball, you don't know nothin'"...Yogi Berra