1. Wichtl M. Herbal Drugs and Phytopharmaceuticals. Boca Raton, FL: CRC Press, 1994, 305-8.
2. Bradley PR (ed). British Herbal Compendium. Bournemouth: British Herbal Medicine Association, 1992, 128-30.
3. Eagon CL, Elm MS, Eagon PK. Estrogenicity of traditional Chinese and Western herbal remedies. Proc Annu Meet Am Assoc Cancer Res 1996;37:A1937 [abstract].
4. Brown DJ. Herbal Prescriptions for Better Health. Rocklin, CA: Prima Publishing, 1996, 279.
5. Blumenthal M, Busse WR, Goldberg A, et al. (eds). The Complete German Commission E Monographs: Therapeutic Guide to Herbal Medicines. Austin: American Botanical Council and Boston: Integrative Medicine Communications, 1998, 147, 160-1.
6. Koetter U, Schrader E, Käufeler R, Brattström A. A randomized, double blind, placebo-controlled, prospective clinical study to demonstrate clinical efficacy of a fixed valerian hops extract combination (Ze 91019) in patients suffering from non-organic sleep disorder. Phytother Res 2007;21:847-51.
7. Murray MT. The Healing Power of Herbs. Rocklin, CA: Prima Publishing, 1995.
8. Murray MT. The Healing Power of Herbs. Rocklin, CA: Prima Publishing, 1995.
9. Weiss RF. Herbal Medicine. Gothenburg, Sweden: Ab Arcanum, 1988, 285-6.
10. Foster S. Herbs for Your Health. Loveland, CO: Interweave Press, 1996, 56-7.
11. Blumenthal M, Busse WR, Goldberg A, et al. (eds). The Complete Commission E Monographs: Therapeutic Guide to Herbal Medicines. Boston, MA: Integrative Medicine Communications, 1998, 147.
12. Foster S. Herbs for Your Health. Loveland, CO: Interweave Press, 1996, 56-7.