Hasan Ali, A. ., Salih Ahmed, F. ., & Abdulkareem Mohammed, K. . (2009). A Computer Aided Design for Internal Spur and Helical Gears. Journal of Engineering and Sustainable Development, 13(1), 166-178. https://jeasd.uomustansiriyah.edu.iq/index.php/jeasd/article/view/1566