• Jennings, J. R., Bberg, W. K., Hutcheson, J. S., Obrist, P., Porges, S., & Turpin, G. (1981). Publication guidelines for heart rate studies in man. Psychophysiology, 18(3), 226-231.

• Electrodes positions and recording practices (Biopac application note) 109
• Automated ECG analyses (Biopac application note) 148
• R-R intervals processing for HRV (Biopac application note) 246
• R wave identification improvement note (Sylvain Delplanque)

Heart rate variability is computed from ECG signals

Pulse rate variability is computed from PPG signals

• Billman, G. E. (2007). Heart rate variability–a historical perspective. Heart Rate Variability: Clinical Applications and Interaction between HRV and Heart Rate, 9.

• Task Force of the European Society of Cardiology. (1996). Heart rate variability: standards of measurement, physiological interpretation, and clinical use. circulation, 93, 1043-1065.
• Berntson, G. G., Thomas Bigger, J., Eckberg, D. L., Grossman, P., Kaufmann, P. G., Malik, M., … Van Der Molen, M. W. (1997). Heart rate variability: Origins, methods, and interpretive caveats. Psychophysiology, 34(6), 623-648.
• Acharya, U. R., Joseph, K. P., Kannathal, N., Lim, C. M., & Suri, J. S. (2006). Heart rate variability: a review. Medical and biological engineering and computing, 44(12), 1031-1051.
• Allen, J.J.B., Chambers, A.S., & Towers, D.N. (2007). The many metrics of cardiac chronotropy: A pragmatic primer and a brief comparison of metrics. Biological Psychology, 74, 243–262.
• Draghici, A. E., & Taylor, J. A. (2016). The physiological basis and measurement of heart rate variability in humans. Journal of physiological anthropology, 35 (1), 22.
• Laborde S., Mosley E., Thayer J. F. (2017). Heart rate variability and cardiac vagal tone in psychophysiological research – recommendations for experiment planning, data analysis, and data reporting . Front. Psychol. 8 :213.
• Shaffer, F., & Ginsberg, J. P. (2017). An overview of heart rate variability metrics and norms. Frontiers in public health, 5, 258.
• de Geus, E. J., Gianaros, P. J., Brindle, R. C., Jennings, J. R., & Berntson, G. G. (2019). Should heart rate variability be “corrected” for heart rate? Biological, quantitative, and interpretive considerations.Psychophysiology, 56 (2), e13287.

• Shaffer, Fred, and J. P. Ginsberg. "An overview of heart rate variability metrics and norms." Frontiers in public health 5 (2017): 258.

Preparing data for analysis 233
Analysis: statistical measures 129

Many of those soft/toolboxes process HRV or PRV from inter beat interval (IBI) time series but may contain their own algorithms to extract IBI time series from the raw/filtered signals.

• ARTiiFACT- A tool for heart rate artifact processing and heart rate variability analysis.
• HRVAS is a complete and self-contained heart rate variability analysis software (HRVAS) package.
• Kubios HRV software is a scientific tool for heart rate variability analysis.Facebook Page
• QRSTool and CMetX Software for Calculating Metrics of Cardiac Variability
• RR-APET - A robust, multi-platform, open-source, heart rate variability (HRV) software.

• Sherwood, A., Allen, M. T., Fahrenberg, J., Kelsey, R. M., Lovallo, W. R., & van Doornen, L. J. P. (1990). Methodological guidelines for impedance cardiography. Psychophysiology, 27(1), 1-23.

Review papers on the different measures derived from PPG:

• Allen, J. (2007). Photoplethysmography and its application in clinical physiological measurement. Physiological measurement, 28 (3), R1.
• Elgendi, M. (2012). On the Analysis of Fingertip Photoplethysmogram Signals. Current Cardiology Reviews, 8 (1), 14–25.
• Elgendi, M. (2012). Standard Terminologies for Photoplethysmogram Signals. Current Cardiology Reviews, 8 (3), 215–219.
• Elgendi, M., Norton, I., Brearley, M., Abbott, D., & Schuurmans, D. (2014). Detection of a and b waves in the acceleration photoplethysmogram. Biomedical engineering online, 13 (1), 139.

Laser speckle contrast imaging (LSCI) is a novel non-invasive microvascular imaging modality.

• Microcirculation: Basic principles
• Real time microcirculation imaging systems PeriCam PSI
• Laser Speckle Contrast Imager, Moor Instruments

• Humeau-Heurtier, A., Guerreschi, E., Abraham, P., & Mahé, G. (2013). Relevance of laser Doppler and laser speckle techniques for assessing vascular function: state of the art and future trends. IEEE transactions on biomedical engineering, 60(3), 659-666.
• Vaz, P. G., Humeau-Heurtier, A., Figueiras, E., Correia, C., & Cardoso, J. (2016). Laser speckle imaging to monitor microvascular blood flow: a review. IEEE reviews in biomedical engineering, 9, 106-120.

• Mahé, Guillaume, et al. "Distance between laser head and skin does not influence skin blood flow values recorded by laser speckle imaging." Microvascular research 82.3 (2011): 439-442.
• Rousseau, Pascal, et al. "Increasing the “region of interest” and “time of interest”, both reduce the variability of blood flow measurements using laser speckle contrast imaging." Microvascular research 82.1 (2011): 88-91.
• Mahé, Guillaume , et al. "Air movements interfere with laser speckle contrast imaging recordings." Lasers in medical science 27.5 (2012): 1073-1076.
• Zötterman, J., Mirdell, R., Horsten, S., Farnebo, S., & Tesselaar, E. (2017). Methodological concerns with laser speckle contrast imaging in clinical evaluation of microcirculation. PloS one, 12(3), e0174703.
• Humeau-Heurtier, A., Mahé, G., & Abraham, P. (2015). Microvascular blood flow monitoring with laser speckle contrast imaging using the generalized differences algorithm. Microvascular research, 98, 54-61.
• Omarjee, L., Signolet, I., Humeau-Heutier, A., Martin, L., Henrion, D., & Abraham, P. (2015).Optimisation of movement detection and artifact removal during laser speckle contrast imaging. Microvascular research, 97, 75-80.

• Pauling, John D., et al. "Comparison of infrared thermography and laser speckle contrast imaging for the dynamic assessment of digital microvascular function." Microvascular research 83.2 (2012): 162-167.
• Humeau-Heurtier, A., Mahe, G., Durand, S., & Abraham, P. (2013). Skin perfusion evaluation between laser speckle contrast imaging and laser Doppler flowmetry. Optics Communications, 291, 482-487.