1. Prather, M. et al. Nature 381, 551–554 (1996).
2. Montzka, S. A. et al. Nature 398, 690–694 (1999).
3. Oberthur, S. Production and Consumption of Ozone-Depleting Substances 1986-1995 (Deutsche Gesellschaft für Technische Zusammenarbeit, Berlin, 1997).
4. Velders, G. J. M. & Madronich, S. in Scientific Assessment of Ozone Depletion: 1998 Ch. 11 (UNEP/WMO, in the press).
5. Butler, J. H. et al. J. Geophys. Res. 103, 1503–1511 (1998).