Rahmat Setiadi, Bayu, Thomas Sukardi, and Sugiyono . “Mobile Technical Calculators With a Flipped Classroom for Sustainability Machining Process”. International Journal of Engineering and Technology 7, no. 3.2 (June 20, 2018): 741–746. Accessed August 17, 2025. https://mail.sciencepubco.com/index.php/IJET/article/view/18740.