1. DIN Standard 3992, Addendum modification of external spur and helical gears.
2. DIN Standard 3994, Addendum modification of straight spur gears in the 05-system.
3. DIN Standard 3995, Straight external spur gears in the 05-system.
4. Tratado Teórico-Práctico de Elementos de Máquinas;Niemann,1973
5. Traité Théorique et Practique des Engrenages;Henriot,1979