1. Gonfiantini, R., and Picciotto, E., Nature, 184, 1557 (1959).
2. de Maere, X., Exp. Antarct. Belge, 1957–58, Rapports scientifiques, Météo.
3. Craig, H., and Boato, G., “Ann. Rev. Phys. Chem.”, 6, 414 (1955).
4. Epstein, S., I.G.Y. Bull., No. 21 (1959).
5. Dansgaard, W., Nief, G., and Roth, E., Nature, 185, 232 (1960).