Validation of Photoplethysmography as a Method to Detect Heart Rate During Rest and Exercise
Spierer, D. K., Rosen, Z., Litman, L., & Fujii, K. (2015). Validation of photoplethysmography as a method to detect heart rate during rest and exercise. Journal of Medical Engineering and Technology, 39(5), 264-271.
The original material can be found here: doi:10.3109/03091902.2015.1047536.