1. Corrin, M.: J. Chem. Ed. 55, 210 (1978)
2. Leith, H.: Vegetation and CO2 changes. In: Carbon dioxide, climate, and society. Williams, J. (ed.), p. 104. Oxford: Pergamon 1978
3. The population density for United States cities is 360 people per square mile, with 60% of the population living in cities. (Statistical Abstract of the United States, Washington, D.C.: U. S. Dept. of Commerce, p. 19, 1977). Since many cities in other countries are somewhat more densely populated, a world average figure of 400 people per square mile is assumed. For a 1978 world population of 4,2 billion, the resulting global urban area is that given in Table 1
4. Rasmussen, R.A.: EOS-Trans. AGU 59, 1082 (1978)
5. Schmidt, U.: J. Geophys. Res. 83, 941 (1978)