K. Matsumoto, T. Nakanishi, T. Sakawa, K. Onodera, S. Orimo, and H. Kobayashi, “AI-Josyu: Thinking Support System in Class by Real-time Speech Recognition and Keyword Extraction”, EMITTER Int’l J. of Engin. Technol., vol. 7, no. 1, pp. 366-383, Jun. 2019.