1. Anderson, J. A., and Wood, H. O.,Description and Theory of the Torsion Seismometer, Bull. Seism. Soc. Amer. 15, 1 - 72 (1925).
2. Bath, M.,Development of Instrumental Seismology in Sweden in 1949-1958, Geofis. pura e appl. 43, 108 - 130 (1959).
3. Benioff, H.,A New Vertical Seismograph. Bull. Seism. Soc. Amer. 22, 155 - 169 (1932).
4. Benioff, H.,A Linear Strain Seismometer. Bull. Seism. Soc. Amer. 25, 283 - 309 (1935).
5. Benioff, H.,Earthquake Seismographs and Associated Instruments, Advances in Geophys. 2, 219 - 275 (1955).