“A Computer Aided Design for Internal Spur and Helical Gears”, J. eng. sustain. dev., vol. 13, no. 1, pp. 166–178, Mar. 2009, Accessed: Jul. 22, 2024. [Online]. Available: https://jeasd.uomustansiriyah.edu.iq/index.php/jeasd/article/view/1566