1. Bush, T., Mooney, D., and Loader, A. (1998). UK NO 2 Diffusion Tube Network Instruction Manual. AEA Technology, National Environmental Technology Centre. Report AEAT-3675.
2. Clark, I. (1977). Regularization of a semivariogram, Computers and Geosciences, 3:341–346.
3. Commission of the European Communities (1985). Council Directive of 7 March 1985 on Air Quality Standards for Nitrogen Dioxide. (85/203/EEC) O.J. L 87 27/03/85 pp 1–7.
4. Department of Health (1997). Quantification of the effects of air pollution on health in Great Britain. Committee on the Medical Effects of Air Pollutants. The Stationary Office.
5. Department of the Environment (1997). The United Kingdom National Air Quality Strategy. The Stationary Office.