S. O. Abiola, S. Molemo, M. E. Muluvhu, M. V. Zitholele, K. Sephai, and W. K. Kupolati, “IMPROVING THE STRENGTH PROPERTIES OF SUBGRADE SOILS WITH FLY ASH”, laujet, vol. 10, no. 2, pp. 79–83, Aug. 2016.