1. Bishop , L. W. J. Hill Analysing stratospheric ozone for natural and man-made trends 1981
2. Frequency domain estimation of trends in stratospheric ozone;Bloomfield;J. Geophysical Research
3. Analyzing worldwide total ozone for trends;Hill;Geographical Research Letters,1977
4. NAS (National Academy of Sciences) Report Stratospheric Ozone Depletion by Halocarbons: Chemistry and Transport National Research Council Washington DC 1979