1. Smith, J. E., and Bryan, Samuel: Studies of Frequency Response in Ballistocardiography. Am. Heart J. In publication.
2. A Bar Magnet Velocity Meter;Perls;The Review of Scientific Instruments,1951
3. Smith, J. E., Perls, T. A., and Kissinger, C. W.: An Integrating and Differentiating Bar Magnet Velocity Meter for Use in Ballistocardiography. In preparation.
4. Dock, W.: Personal communication.