1. Delmas, R. J., Ascencio, J.-M. & Legrand, M. Nature 284, 155–157 (1980).
2. Stuiver, M., Burk, R. L. & Quay, P. D. J. geophys. Res. 89, 11713–11748 (1984).
3. Neftel, A., Moore, E., Oeschger, H. & Stauffer, B. Nature 315, 45–47 (1985).
4. Keeling, C. D. et al. in Aspects of Climate Variability in the Pacific and the Western Americas (ed. Peterson, D. H.) 165–236 (American Geophysical Union, Washington DC, 1989).
5. Henderson, S. A., von Caemmerer, S. & Farquhar, G. D. Aust J. Plant Physiol. 19, 363–386 (1992).