Shafiq, Nasir, and M Fadhil Nuruddin. “Degree of Hydration of OPC and OPC Fly Ash Paste Samples Conditioned at Different Relative Humidity”. International Journal of Sustainable Construction Engineering and Technology, vol. 1, no. 1, May 2011, pp. 47-56, https://penerbit.uthm.edu.my/ojs/index.php/IJSCET/article/view/51.