Harry G. Poulos. “Rational Assessment of Modulus of Subgrade Reaction”. Geotechnical Engineering Journal of the SEAGS & AGSSEA 49, no. 1 (March 31, 2018): 1–7. accessed September 12, 2026. https://ph01.tci-thaijo.org/index.php/SEAGS_AGSSEA_Journal/article/view/259143.