1. K. Yamakoshi, and T. Togawa, “Biosensors and Measurement Devices,” Corona Publishing, 2000.
2. B.-H. Yang, S. Rhee, and H. Asada, “A Twenty-Four Hour Tele-Nursing System Using a Ring Sensor,” IEEE International Conference on Robotics and Automation (ICRA98), pp. 387-392, 1998.
3. S. Carlson, “Home is where the ECG is,” Scientific American June, p. 86, 2000.
4. K. Kobayashi, “Diagnosis Engineering,” Corona Publishing, 2000.