T. Y. Yin, F. Mahmud, and N. I. Ramli, “Near-Infrared Spectroscopy (NIRS)-based Digit Skin Tissue Blood Flow Measurement System”, IJET, vol. 7, no. 4.30, pp. 131–135, Nov. 2018, doi: 10.14419/ijet.v7i4.30.22076.