1. O'Dowd, C. D. et al. Nature 417, 632–636 (2002).
2. Houghton, J. T. et al. (eds) Climate Change 2001: The Scientific Basis (Cambridge Univ. Press, 2001).
3. Rosenfeld, D. Geophys. Res. Lett. 26, 3105–3108 (1999).
4. Rosenfeld, D. Science 287, 1793–1796 (2000).
5. Seinfeld, J. H. & Pandis, S. N. Atmospheric Chemistry and Physics (Wiley, New York, 1998).