1. Libby, L. M. et al. Nature 261, 248–288 (1976).
2. Dansgaard, W., Johnsen, S. J., Clausen, H. B. & Langway, H. J. Nature 227, 482–483 (1971).
3. Roosen, R. G., Harrington, R. S., Giles, J. & Browning, I. Nature 261, 680–682 (1976).
4. Blackman, R. B. & Tukey, J. W. The Measurement of Power Spectra (Dover New York, 1958).
5. Dansgaard, W. Tellus XV0, 436–468 (1964).