1. Malliani A. The pattern of sympathovagal balance explored in the frequency domain. News Physiol Sci. 1999;14:111–7.
2. Low PA, editor. Clinical autonomic disorders: evaluation and management. Philadelphia: Lippincott-Raven; 1997.
3. Low PA, Benarroch EE, editors. Clinical autonomic disorders. Philadelphia: Lippincott Williams and Williams; 2008.
4. Low PA, Engstrom JW. Disorders of the autonomic nervous system. In: Harrison’s principles of internal medicine. 16th ed. New York: McGraw-Hill; 2003.
5. Hales S. Statistical essays, vol. II. 1733rd ed. London: Haemastaticks: Innings and Manby; 1733.