1. Description and theory of the torsion scismolograph;Anderson;Bull. Seismol. Soc. Am.,1925
2. Development of seismological instruments at the Bureau of Standards;Wenner;Bull. Seismol. Soc. Am.,1932
3. McComb, H. E. (1936). Earthquake investigation in California 1934--1935. U. S. Coast and Geodetic Survey Special Publ. No. 201, p. 6.