1. 1FRIEDMAN I. AND OUGHTERSON A. W.: Oscillonietry. Library of AMed. and Surg. Suppl. 1938. New York D. Appleton-Century Co. 1938. P. 97.
2. Clinical plethysniography;GOETZ R. H.;South African M. J.,1948
3. Electrokyrnograph fir recording heart nc ti mn, improved type;HENNY G. C.;Am. J. Roentgenol.,1947