3) Cornolo J, Mollard P, Brugniaux J.V et al.: Autonomic control of the cardiovascular system during acclimatization to high altitude: effects of sildenafil. J Appl Physiol 97: 935-940, 2004.
5) Akselrod S, Gordon D, Ubel FA, et al.: Power spectrum analysis of heart rate fluctuation: a quantitative probe of beat-to-beat cardiovascular control. Science 213: 220-222, 1981.