1. 1) Kubo M, Asano T, Matsuda H, Yutani S, Honda S. Studies on Rehmanniae radix. III. The relation between changes of constituents and improvable effects on hemorheology with the processing of roots of Rehmannia glutinosa. Yakugaku Zasshi, 116, 158–168 (1996).
2. 2) Ministry of Health, Labour and Welfare. “The Japanese pharmacopoeia eighteenth edition (Ministry Notification No. 220 of Jun. 7, 2021). The Ministry of Health, Labour and Welfare, Japan (2021).”: ‹https://www.mhlw.go.jp/content/11120000/000788359.pdf›, accessed 28 December, 2021.
3. 3) Chongxiuzhenghejingshizhengleibeiyongbencao (1108), facsimile edition (Tang SW ed.), People’s Medical publishing House Co., LTD., Beijing, p. 149 (1957).
4. 4) Huang YT, Ando H, Tsujino M, Yoshihara K, Sasaki Y. Studies on stability of catalpol contained in the root of Rehmannia glutinosa. The Japanese Journal of Medicinal Resources, 43, 10–20 (2021).
5. 5) Ji XQ, Sun P, Qi JJ, Liao DQ, Li XE. Study on distribution and dynamic accumulation of catalpol and total iridoid in fresh Rehmannia glutinosa. Zhongguo Zhong Yao Za Zhi., 39, 466–470 (2014).