1. Hypothetically, the new challenges and the pathfinder role of nuclear energy;Häfele;Minerva,1974
2. Energy systems;Häfele;Bulletin of the International Atomic Energy Agency,1974
3. 700,000,000,000 barrels of soot;Sumner;Sierra Club Bulletin,1974
4. See the forthcoming study by R. Avenhaus, W. Häfele and P. McGrath.
5. Reactor strategies and the energy crisis;Häfele,1973