Kazunori Ohtani Tohru Kiryu Yoshiaki Saitoh Extraction of autonomic nervous system-related components from heart rate variability during cycle exercise by time-frequency analysis. 47-56 1999 30 Systems and Computers in Japan 2 http://dx.doi.org/10.1002/(SICI)1520-684X(199902)30:2<47::AID-SCJ6>3.0.CO;2-R db/journals/scjapan/scjapan30.html#OhtaniKS99