- Woodward and the James Leffel Company go way back in history.
- Leffel hydraulic turbines since 1862.
- Leffel Turbines...
- LEFFEL QUALITY...
- THE JAMES LEFFEL AND COMPANY ADVERTISEMENT.
- LEFFEL HYDRAULIC TURBINES.
- James Leffel & Company advertisement.
- IMPULSE TURBINES BY SMITH. BULLETIN 138.
- Elmer Woodward's new oil pressure relay valve water wheel governor ca 1912.