AFOLABI, R.O., ORODU, O.D., EFEOVBOKHAN, V.E., ROTIMI, O.J. and ZHANG, Z. 2017. Optimizing the rheological properties of silica nano-modified bentonite mud using overlaid contour plot and estimation of maximum or upper shear stress limit. Cogent engineering [online], 4(1), article 1287248. Available from: https://doi.org/10.1080/23311916.2017.1287248