1. AGMA Standard 2001-B88, Fundamental rating factors and calculation methods for involute spur and helical gears.
2. Tratado Teórico-Práctico de Elementos de Máquinas;Niemann,1973
3. DIN Standard 3992, Addendum modification of external spur and helical gears.
4. Traité Théorique et Practique des Engrenages;Henriot,1979
5. Design of nonstandard spur gears cut by a hob