1. Bradley, R. S. et al. Science 237, 171–175 (1987).
2. Diaz, H. F., Bradley, R. S. & Eischeid, J. K. J. geophys. Res. 94, 1195–1210 (1989).
3. Eischeid, J. K., Diaz, H. F., Bradley, R. S. & Jones, P. D. A Comprehensive Precipitation Data Set for Global Land Areas (Rep. DOE/ER-690017T-H1, US Dept of Energy, Washington DC, 1991).
4. Karl, T. R., Knight, R. W. & Plummer, N. Nature 377, 217–220 (1995).
5. Nicholls, N. et al. in Climate Change 1995: The Science of Climate Change (eds Houghton, J. T. et al.) 137–181 (Cambridge Univ. Press, Cambridge, 1996).