5HANDSCHUH R, LEWICKI D, BOSSLER R. Experimental Testing of Prototype Face-Gears for Helicopter Transmissions[R]. Solihull: NASA Technical Memorandum 105434, 1992: 1-10.
6LITVIN F L, CHEN N X, CHEN J S. Computerized Determination of Curvature Relations and Contact Ellipse for Conjugate Surfaces[J]. Computer Methods in Applied Mechanics andEngineering, 1995, 125(1): 151-170.
7LITVIN F L, ZHANG Y, WANG J C, et al. Design and Geometry of Face-Gear Drives[J]. Journal of Mechanical Design, 1992, 114(4):642-647.