1. The mechanical amplification of small displacements;POLLARD;J. Sci. Instrum.,1938
2. A. C. RUGE and E. O. SCHMIDT, Mechanical structural analysis by the moment indicator, Proc. Am. Soc. Civil Eng. (1938).
3. Characteristics of the Huggenberger strain gage;CUYKENDALL;Civ. Eng. (New York).,1940
4. The measurement of stresses in framed structures;HAWKES;Civ. Eng. and Pub. Wks. Rev.,1952
5. R. A. SEFTON JENKINS, Testing of Prestressed Steelwork, Prelim. vol., Conf. on the Correlation between Calculated and Observed Stresses in Structures, pp. 44–53. Inst. C.E., London, 1955.