Mannan, A., S. . I. Hussain, S. Ehsan, and M. . S. Khan. “SPECTROSCOPIC AND CHEMICAL EVALUATION OF CLAY MINERALS AND THEIR SUITABILITY FOR THE MANUFACTURING OF ORGANIC CLAY, MEDICINAL CLAY AND PILLARED CLAY”. Biological Sciences - PJSIR, vol. 47, no. 6, Dec. 2004, pp. 407-16, http://v2.pjsir.org/index.php/biological-sciences/article/view/1561.