S. Kulkarni, Vishakha, and Sanjay J. Surana. “Simultaneoous Estimation of Piperne and 6-Gingerol in an Ayurvedic Formulation by HPLC”. Asian Journal of Chemistry, vol. 24, no. 5, Jan. 2012, pp. 1983-6, https://asianpubs.org/index.php/ajchem/article/view/8922.