Koteswara Rao, Dr.D. 2021. “Laboratory Studies on the Efficacy of Palm Oil Fuel Ash and Phosphogypsum for Improving the Properties of Expansive Soil As Subgrade for Flexible Pavements”. International Journal of Technical Innovation in Modern Engineering & Science 6 (10):06-16. https://ijtimes.com/index.php/ijtimes/article/view/76.