Tahir, M., N. Mohammad, and F. Din. “ Strength Parameters and Their Inter-Relationship for Limestone of Cherat and Kohat Areas of Khyber Pakhtunkhwa ”. Journal of Himalayan Earth Sciences, vol. 44, no. 2, Nov. 2011, pp. 45-51, http://ojs.uop.edu.pk/jhes/article/view/1638.