1) Tamura M., “Useful Plant of The World,” ed. by Hotta M., Ogata K., Nitta A., Hoshikawa K., Yanagi M., Yamazaki K., Heibon Ltd., Tokyo, 1989, p. 268.
2) Ohwi J., “Flora of Japan”, Shibundo, Tokyo, 1965, p. 632.
3) Mitsuhashi H., “Illustrated Medicinal Plants of The World in Colour,” Hokuryukan Co., Ltd., Tokyo, 1988, pp. 87-90.
4) “The Interpretation of The Japanese Pharmacopeia XIII,” 1st Addition, Hirokawa, Tokyo, 1998, D-11.