1. Meinel, A. B. & Meinel, M. P. Applied Solar Energy, An Introduction (Addison–Wesley, Massachusetts, 1976).
2. Weber, W. H. & Lambe, J. Appl. Phys. 15, 2299–2300 (1976).
3. Lieblich-Sofer, N., Reisfeld, R. & Jørgensen, C. K. Inorg. chim. Acta (in the press).
4. Jørgensen, C. K. Acta chem. scand. 11, 166–178 (1957).
5. Jørgensen, C. K. & Reisfeld, Chim. phys. Lett. 35, 441–443 (1975).