Zenico T, Cicero AFG, Valmorri L, Mercuriali M, Bercovich E. Subjective effects of Lepidium meyenii (Maca) extract on well-being: a randomised, double-blind clinical trial. Andrologia. 2009;41(2):95–99.

Raghav S, Singh H, Dalal PK, Srivastava JS, Asthana OP, 2006. Randomized controlled trial of standardized Bacopa monniera extract in age-associated memory impairment. Indian Journal of Psychiatry, 48, 238.

Roodenrys S, Booth D, Bulzomi S, Phipps A, Micallef C, Smoker J, 2002. Chronic effects of Brahmi (Bacopa monnieri) on human memory. Neuropsychopharmacology, 27, 279-281.

Stough C, Lloyd J, Clarke J, Downey LA, Hutchison CW, Rodgers T, Nathan PJ, 2001. The chronic effects of an extract of Bacopa monniera (Brahmi) on cognitive function in healthy human subjects. Psychopharmacology (Berl), 156, 481-484.

Bhattacharya SK, Bhattacharya A, Kumar A, Ghosal S, 2000. Antioxidant activity of Bacopa monniera in rat frontal cortex, striatum and hippocampus. Phytother Res, 14, 174-179.

Williamson EM, 2002. Major Herbs of Ayurveda. Churchill Livingstone, London, Edinburgh.

Blumenthal M, 1994. The Complete German Commission E Monographs: Therapeutic Guide to Herbal Medicines The American Botanical Council.

Brautigam MRH, Blommaert FA, Verleye G, Castermans J, Steur E, Kleijnen J, 1998. Treatment of age- related memory complaints with Ginkgo biloba extract: a randomized double blind placebo-controlled study. Phytomedicine, 5, 425-434.

ESCOP (The European Scientific Cooperative on Phytotherapy), 2003. ESCOP Monographs: The Scientific Foundation of Herbal Medicinal Products. Thieme, Stuttgart.

Grassel E, 1992. Effect of Ginkgo-biloba extract on mental performance. Double-blind study using computerized measurement conditions in patients with cerebral insufficiency. Fortschr Med, 110, 73-76.

Heinen-Kammerer VT, Motzkat K, Daniel D, Gertz HJ, Koller M, Lorenz W, Pilartz H, Zimmer B, Habs M, von den Driesch V, Rychlik R, 2005. The situation of patients with dementia may be rectified by Gingko Biloba. MMW Fortschr Med, 147, 51.

Le Bars PL, Katz MM, Berman N, Itil TM, Freedman AM, Schatzberg AF, 1997. A placebo-controlled, double-blind, randomized trial of an extract of Ginkgo biloba for dementia. North American EGb Study Group. JAMA, 278, 1327-1332.

Rigney U, Kimber S, Hindmarch I, 1999. The effects of acute doses of standardized Ginkgo biloba extract on memory and psychomotor performance in volunteers. Phytother Res, 13, 408-415.

Soholm B, 1998. Clinical improvement of memory and other cognitive functions by Ginkgo biloba: review of relevant literature. Adv Ther, 15, 54-65.

Solomon PR, Adams F, Silver A, Zimmer J, DeVeaux R, 2002. Ginkgo for memory enhancement: a randomized controlled trial. JAMA, 288, 835-840.

WHO (World Health Organization), 1999. WHO Monographs on Selected Medicinal Plants. WHO (World Health Organization), Geneva.

Blaschek W, Ebel S, Hackenthal E, Holzgrabe U, Keller K, Reichling J, Schulz V, 2004. HagerROM 2004. Hagers Handbuch der Drogen und Arzneistoffe. Springer Verlag, Heidelberg.

Brendler T, Gruenwald J, Jaenicke C, 1997. Herbal Remedies: Heilpflanzen. Deutscher Apotheker Verlag, Stuttgart.

D'Angelo L, Grimaldi R, Caravaggi M, Marcoli M, Perucca E, Lecchini S, Frigo GM, Crema A, 1986. A double-blind, placebo-controlled clinical study on the effect of a standardized ginseng extract on psychomotor performance in healthy volunteers. J Ethnopharmacol, 16, 15-22.

Ellis JM and Reddy P, 2002. Effects of Panax ginseng on quality of life. Ann Pharmacother, 36, 375-379.

Kennedy DO, Scholey AB, Wesnes KA, 2001. Dose dependent changes in cognitive performance and mood following acute administration of Ginseng to healthy young volunteers. Nutr Neurosci, 4, 295-310.

Van Wyk BE, 2005. Handbuch der Nutzpflanzen. Wissenschaftliche Verlagsgesellschaft, Stuttgart.

Wichtl M, 2001. Herbal Drugs and Phytopharmaceuticals. Medpharm Scientific Publishers, Stuttgart.

Barnes J, Anderson LA, Phillipson JD, 2003. Herbal Medicines. Pharmaceutical Press, London.

Hallstrom C, Fulder S, Carruthers M, 1982. Effects of ginseng on the performance of nurses on night duty. Comp Med East West, 6, 15-22.

Keifer D and Pantuso T, 2003. Panax ginseng. American Family Physician, 68, 1539-1542.

Brendler T, Gruenwald J, Jaenicke C, 2003. Herbal Remedies: Heilpflanzen. Deutscher Apotheker Verlag, Stuttgart.

Bucci LR, 2000. Selected herbals and human exercise performance. Am J Clin Nutr, 72, 624S-636S.

Coleman CI, Hebert JH, Reddy P, 2003. The effects of Panax ginseng on quality of life. J Clin Pharm Ther, 28, 5-15.

Kennedy DO and Scholey AB, 2003a. Ginseng: potential for the enhancement of cognitive performance and mood. Pharmacol Biochem Behav, 75, 687-700.

Kennedy DO, Scholey AB, Drewery L, Marsh VR, Moore B, Ashton H, 2003b. Electroencephalograph effects of single doses of Ginkgo biloba and Panax ginseng in healthy young volunteers. Pharmacol Biochem Behav, 75, 701-709.

Kim SH, Park KS, Chang MJ, Sung JH, 2005. Effects of Panax ginseng extract on exercise-induced oxidative stress. J Sports Med Phys Fitness, 45, 178-182.

Reay JL, Kennedy DO, Scholey AB, 2005. Single doses of Panax ginseng (G115) reduce blood glucose levels and improve cognitive performance during sustained mental activity. J Psychopharmacol, 19, 357- 365.

Mahady GB, Gyllenhaal C, Fong HHS, Farnsworth NR, 2000. Ginsengs: a review of safety and efficacy. Nutrition in Clinical Care, 3, 90-101.

Wren RC and Williamson EM, 2003. Potter's Herbal Cyclopaedia. C.W. Daniel Co Ltd, Saffron Walden.

Flynn R and Roest M, 1995. Your guide to standardized herbal products. One World Press, Prescott, Arizona.