Randomised, controlled trial of ginkgo biloba and acetazolamide for prevention of acute mountain sickness: the prevention of high altitude illness trial (PHAIT), Gertsch, J, H.; Buddha Basnyat,; Johnson, E, W.; Onopa, J,; Holck, P, S. , British Medical Journal (Clinical Research edition), Number No.7443, p.797-799, (2004) Abstract