A. L. Gottumukkala, T. Ramakrishna, S. Kanna Babu, and G. V. Subbaraju, “Determination of (E) & (Z)-Guggulsterones in Guggul Formulations by High Performance Liquid Chromatography”, ajc, vol. 17, no. 3, pp. 1789–1793, May 2016.