1. 2) Hotta M, Ogata K, Nitta A, Hoshikawa K, Yanagi M, and Yamazaki K, “Useful Plants of the World” (in Japanese), Heibonsya, Tokyo (1989).
2. 3) Hayashi Y, “Wild Flowers of Japan” (in Japanese), Yama-Kei Publishers, Tokyo (1983).
3. 4) Digital Museum of Natural History, Hiroshima University, Hiroshima (2003–2010).