1Einthoven W. The string-galvanometer and the human electro- cardiogram. Proceed Section of Sciences Koninklijke Akademie van Wetenschappen te Amsterdam, Proceedings of the Section of Sciences[-J~. Kon Akad Wet Amsterdam, 1903,6 : 107.
2H offman BF, de Carvalho AP, Mello WC, et al. Electrical activ- ity of single fibers of the atrioventricular node[J]. Cireulation Res,1959, 7:11.
3Liu RG. An attempt of "new wavelet" analysis on electrocardi- ogram in locating the site of atrioventricular blockEJ~. Interna- tional Journal of Cardiology, 2015, (189) :228.
4Liu RG, Chang QH, Chen J. New micro waveforms firstly re- corded on electrocardiogram in human[-J]. Medcal Hypotheses, 2015, 85 (4):475.
5Hall JE. Textboob of Medical Physiologyl-M]. 12th Edition. Elsevier Inc. 2011. 116--117.