Ashkenazy, YosefGoldberger, Ary L.Havlin, ShlomoIvanov, Plamen Ch.Peng, Chung-K.Stanley, H. Eugene2004-12-102004-12-1020012001http://hdl.handle.net/2003/1851610.17877/DE290R-16170enThe American Physical SocietyPhysical Review Letters530Magnitude and Sign Correlations in Heartbeat Fluctuations10.1103/PhysRevLett.86.1900article (journal)