1. Montreal Protocol on Substances that Deplete the Ozone Layer (United Nations Environment Programme, Nairobi, 1987).
2. UK Stratospheric Ozone Review Group, Stratospheric Ozone 1988, (HMSO, London, 1988).
3. Fisher, D.A. et al. Nature 344, 508–512 (1990).
4. Fisher, D.A., Hales, C.H., Wang, W-C., Ko, M.K.W. & Sze, N.D. Nature 344, 513–516 (1990).
5. Wigley, T.M.L. Nature 335, 333–335 (1988).