Ordinal pattern statistics for the assessment of heart rate variability G. Graff, B. Graff, A. Kaczkowska, D. Makowiec, J.M. Amigó, J. Piskorski, K. Narkiewicz and P. Guzik Eur. Phys. J. Special Topics, 222 2 (2013) 525-534 Published online: 25 June 2013 DOI: 10.1140/epjst/e2013-01857-4