Believe it or not, there was one year when the Dodgers wore green, not blue. It was 1937, and while no color photographs appear of the players or coaches wearing these uniforms, artifacts have surfaced in recent years which prove they existed, in addition to newspaper articles of the day.
The green uniforms only lasted one year, and by 1938 the team was back to Dodger Blue.
Peter enlisted the help of many friends and employees to look in newspapers for any mention of uniform colors by the sportswriters of the day. People like Bill Lipinski and Bob Downs would look in the microfiche to see what they could find.
Generally, the day before opening day, the day of opening day, and/or the day after opening day of a new season would be where the journalists would mention any changes to the color schemes or designs of the uniforms for the local teams.