Fujiwara, S. , Kaburagi, T. , Kobayashi, K. , Watanabe, K. , Kurihara, Y. (2015). 'Evaluation Using a Bidirectional Microphone as a Pressure Pulse Wave Meter'. World Academy of Science, Engineering and Technology, Open Science Index 104, International Journal of Health and Medical Engineering, 9(8), 806 - 811.