Reference
- SIEVERT, R. M. 1959, A method for the automatic recording of ionizing radiation. Acta radiologica, Suppl. 188, pp. 224-234, 1959.
- SIEVERT, R. M. 1959, Records of gamma radiation from the ground and beta radiation from radioactive debris in Sweden 1950-1955, Part I, Talus, Vol. 8, pp. 117-126, 1956.
- THOMPSON, TH. and WIBERG, P. A. 1963, Some observations of variations of the natural back-ground radiation. Tellu.s, Vol. 15, pp. 313–318.