Ginting, R., A. M. Tirtayasa, A. F. Malik, and R. Silalahi. “QFD Phases I and II on Walking Aid Case Study”. Journal of Industrial Engineering and Education, vol. 2, no. 1, Apr. 2024, pp. 62-69, https://jiee.bksti.org/index.php/iee/article/view/22.