Singh1, M., et al. “Separation and Simultaneous Quantification of A- and B-Asarone in Acorus Calamus Linn. From Indian Sub-Continent on Caffeine Modified Silica”. Asian Journal of Chemistry, vol. 23, no. 5, Jan. 2011, pp. 2046-8, https://asianpubs.org/index.php/ajchem/article/view/10286.