Ordinal pattern statistics for the assessment of heart rate variabilityG. Graff, B. Graff, A. Kaczkowska, D. Makowiec, J.M. Amigó, J. Piskorski, K. Narkiewicz and P. GuzikEur. Phys. J. Special Topics, 222 2 (2013) 525-534DOI: https://doi.org/10.1140/epjst/e2013-01857-4