|The Afro-American - February 27, 1920|
Gary Ashwill, over at agate type, featured a few articles about the Negro National League's birthday. I found another article that lists the players for each of the six teams.
UPDATE: I found a few more supporting articles.
|The Tulsa Star - February 14, 1920|
|The Tulsa Star - February 28, 1920|