Tawatchai Tanchaisawat, D.T. Bergado, and Taweesak Kanjananak. “Lightweight Geomaterials for Bridge Approach Utilization on Soft Ground Area”. Agriculture and Natural Resources, vol. 41, no. 5, Dec. 2007, pp. 357-63, https://li01.tci-thaijo.org/index.php/anres/article/view/244393.