References
- Riddle H. C., Brydon J. W. E., Willoughby D. A. A capacitance plethysmograph for measuring small volume changes. Biomedical Engineering 1974; 9: 301
- Sigdell J. E. A plethysmograph system with a capacitance displacement transducer and automatic reset. Publication 1:68 of Research Laboratory of Medical Electronics, Chalmers University of Technology, Goteborg, Sweden