1. Designing face gears;Bloomfield;Mach. Design,1947
2. Advanced rotorcraft transmission (ART) program – final report, NASA Contractor Report 191057;Heath,1993
3. G.F. Heath, R.R. Filler, J. Tan, Development of face gear technology for industrial and aerospace power transmission, NASA/CR-2002-211320, May 2002.
4. Torque Splitting By a Concentric Face Gear Transmission, the American Helicopter Society 58th Annual Forum, Montreal;Filler,2002
5. Face Gear Development under the Rotorcraft Drive System for the 21st Century Program, the American Helicopter Society 65th Annual Forum;Heath,2009