1. Aitken, J., Collected Scientific Papers of John Aitken, edited by C. G. Knott. Cambridge, University Press, 1923.
2. Boylan, R. K., “Atmospheric Dust and Condensation Nuclei.” Proc. R. Irish Acad., (A) 37: 58–70 (1926).
3. Bradbury, N. E., “The Absolute Values of the Mobility of Gaseous Ions in Pure Gases.” Phys. Rev., 40: 508–523 (1932).
4. Cullen, T. L., “On the Exhalation of Radon from the Earth.” Terr. Magn. atmos. Elect.,51: 37–44 (1946).
5. Erikson, H. A., “Mobility of Ions.” Phys. Rev., 17: 400 (1921); 18: 100–101 (1921); 20: 117–126 (1922); 24: 502–509 (1924); 26: 465–468 (1925); 28: 372–377 (1926); 29: 215–216 (1927); 33: 403–411 (1929); 34: 635–643 (1929).