1. Brasefield, C. J. (1959),Space Charge in Exhaust of Motor Vehicles, Science29,1610.
2. Chalmers, J. A.,Atmospheric Electricity, 2nd Edn. (Pergamon Press, London (1967).
3. Chree, C., andWatson, R. E. (1924),Atmospheric Pollution and Potential Gradients at Kew Observatory, Proc. R. Soc. Ser. A105, 311.
4. Israel, H. (1950),Zur Entwicklung der luftelektrischen Grundanschauungen Arch. Met, Wien A3, 1.
5. Kelvin, Lord (1860),Electricity, Atmospheric; Nichol's Cyclopaedia, 2nd ed. Papers onElectrostatics andMagnetism.