1. ‘No overdrafts in the energy economy’;Chapman;New Scientist,1973
2. Bravard, J. C., Flora, H. B. and Portal, C. ‘Energy expenditure associated with the production and recycle of metals’, ORNL-NSF-EP 24, Oak Ridge Nat. Labs, 1972
3. ‘Low energy housing’;MacKillop;Ecologist,1972
4. ‘The energy costs of food production’;Leach,1973