- Rockford history.
- Rockford history.
- Vintage Rockford map.
- Rockford factory history.
- 1878 Rockford
- From the archives.
- From the archives.
- A non-Woodward aircraft propeller governor(Curtis-Wright Co.).
- WOODWARD SERIES 1307 AIRCRAFT MAIN ENGINE CONTROL THEORY OF OPERATION.
- Woodward propeller governor with a beta valve.
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- PATENT NUMBER 2,560,758 WITH REFERENCE PATENTS.
- Patent number 2,668,519.
- Patent number 2,668,519. 5 - 6.
- Patent number 2,668,519. 3 - 4.