Tampubolon, H. ., F. Farihah, H. . Hanim, and H. . Bahri. “Development of Interactive E-Books for Production Unit Courses by Implementing a Hybrid Learning System”. International Journal of Educational Research and Social Sciences (IJERSC), vol. 3, no. 6, Dec. 2022, pp. 2433-40, https://ijersc.org/index.php/go/article/view/527.