AHMAD, Z., M. JAVED, S. BAQARI, A. U. HAQAND, and A. KHAN. “?A STUDY OF PAKISTANI GYPSUM BY X-RAY POWDER DIFFRACTION”. Biological Sciences - PJSIR, vol. 39, no. 5-8, Aug. 1996, pp. 110-3, https://v2.pjsir.org/index.php/biological-sciences/article/view/2385.