F.  Zhao, Wang, S. - J., Lin, S., Zhu, C. - G., Yuan, S. - P., Ding, X. - Y., Yue, Z. - G., Yu, Y., Liu, B., Wu, X. - L., and , ?Anthraquinones from the roots of Knoxia valerianoides?, Journal of Asian natural products research, vol. 13, pp. 1023?1029, 2011.