Fujiwara, S. , Kaburagi, T. , Kobayashi, K. , Watanabe, K. , Kurihara, Y.. "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 (2015), 9(8), 806 - 811.