Black History Month: Eastern Iowa proved fertile ground for black baseball
Black baseball before the Negro Leagues - Beyond the Box Score
Life Portrait of James K. Polk, May 28, 1999
MLB Celebrates Black History Month with 'Undeniable' Animated Shorts - Martian Blueberry
Roy Sparrow – Society for American Baseball Research
The Negro Leagues are Major Leagues - AZ Snake Pit
Negro Leagues: A Legacy Remembered
The Negro Leagues are Major Leagues - AZ Snake Pit
MLB Finally Recognizes Negro League Players as Major Leaguers - The Bay State Banner
Pictures tell tale of Negro League legends
Motionographer® Undeniable: The Stories of the Negro Leagues
History of the Negro Leagues, Part Five - Royals Review
How Baseball's Negro Leagues Defied the Stereotypes of Segregation, History
History of the Negro Leagues, Part Five - Royals Review
Polk well represented in Negro League baseball history