Omana, P. K., and M. Santosh. “Morphology of Gold Grains in Laterite Profiles of Nilambur, Kerala: Implications for the Genesis of Supergene Gold Deposits”. Journal of Geological Society of India, vol. 37, no. 6, June 1991, pp. 560-8, https://geosocindia.com/index.php/jgsi/article/view/67320.