1. Mechanisms and Machine Science;E Trubachev,2021
2. Goldfarb, V.I., et al.: Spiroid gears for pipeline valves, Moscow, Veche (2011)
3. Saari, O.: Speed-reduction gearing. Patent USA № 2696125
4. Saari, O.: Skew-axis gearing. Patent USA № 2954704
5. Bohle, F.: Spiroid gear. Machinery 62(2), 155–161 (1955)