author  = "J. Sacha and S. Barabach and G. Statkiewicz-Barabach and K. Sacha and A. Müller and J. Piskorski and P. Barthel and G. Schmidt",
  title   = "How to strengthen or weaken the HRV dependence on heart rate - description of the method and its perspectives",
  journal = "International Journal of Cardiology",
  volume  = "Vol. 168",
  number  = "no. 2",
  pages   = "1660--1663",
  year    = "2013",