1. F.L. Litvin, J.-C. Wang, Y.-J.D. Chen, G. Heath. Face-gear drives Design, analysis, and testing for helicopter transmission applications, NASA. Technical Report 92-C-009, 1992
2. Experiment Testing of Prototype Face Gears for Helicopter Transmissions;Handschuh,1992
3. Gear Geometry and Applied Theory;Litvin,1994
4. Design generation and stress analysis of face-gear drive with helical pinion;Litvin;Comput. Methods Appl. Mech. Eng.,2005
5. Design, generation, and stress analysis of two versions of geometry of face-gear drives;Litvin;Mech. Mach. Theory,2002