- The Proportional Governor Control System.
- The Proportional Governor Control System.
- The Proportional Governor Patent Number 2,474,140.
- The Proportional Governor Control System.
- The Proportional Governor Control System.
- Brad's 80 year old manual that started the Curtiss-Wright Company history search.
- The Proportional Governor Control System.
- Instruction Manual for Curtiss Electric Propellers.
- The Proportional Governor Control System.
- The two lakeside Johnson properties developed over the years.
- The first Hamilton Standard constant speed governor application from the 1930's. The Woodward Governor Company manufactured all their governors.
- The Douglass DC3 Aircraft with the first application of Elmer Woodward's propeller engine governor from patent number 2,204,640.
- Google "Douglass DC-3 aircraft" for history on this legacy aircraft.
- An Aero Digest Aviation Engineering History Project.
- Historically Speaking.