Nurkertamanda, D., I. N. Adiputra, K. Tirtayasa, and I. P. G. Adiatmika. “Enggrong Modification Reduces Low Back Pain Risk on Sand Workers”. International Research Journal of Engineering, IT and Scientific Research, vol. 3, no. 6, Nov. 2017, pp. 31-38, https://sloap.org/journals/index.php/irjeis/article/view/8.