1. Gifford, R. M. Aust. J. Pl. Physiol. 21, 1–15 (1994).
2. Watson, R. T., Rodhe, H., Oeschger, H. & Siegenthaler, U. in Climate Change: The IPCC Scientific Assessment (eds Houghton, J. T., Jenkins, G. J. & Ephraums, J. J.) 1–40 (Cambridge Univ. Press, Cambridge, 1990).
3. Tropical Pastures Program Annual Report 1981 (Centro Internacional de Agricultura Tropical, Cali, Colombia, 1982).
4. Duxbury, J. M., Harper, L. A. & Mosier, A. R. in Agricultural Ecosystem Effects on Trace Gases and Global Climate Change 1–18 (Am. Soc. of Agronomy, Madison, 1993).
5. Vera, R. R., Thomas, R., Sanint, L. & Sanz, J. I. Anais Acad. bras. Cienc. 64 (Supl. 1), 105–125 (1992).