1. Litvin, F. L., 1994, Gear Geometry and Applied Theory, PTR Prentice Hall.
2. Su, X., and Houser, D. R., 1997, Coordinate Measurement and Reverse Engineering of ZK Type Worm Gearing, AGMA 97FTMS1.
3. Kin, V., 1988, Limitations of Worm and Worm-Gear Surfaces in Order to Avoid Undercutting and Appearance of Envelope of Lines in Contact, AGMA 88FTMS1.
4. Litvin, F. L., and Wang, A. G., 1996, “Local Synthesis and Tooth Contact Analysis of Face-Milled, Uniform Tooth Height Spiral Bevel Gears,” NASA Contractor Report 4757.
5. Colbourne, J. R., 1994, Undercutting in Worms and Worm Gears, AGMA 94FTM1.