1. G. B. Airy: Tides and waves. Encycl. metrop., § 208. London 1842.
2. J. E. Fjeldstad: Astrophys. Norv. 3, 10 (1941).
3. P. Kelland: Trans. Roy. Soc. Edinburgh 14, 497 (1893).
4. G. B. Airy: Tides and waves, § 358–363. London 1842.
5. J. Proudman: Phil. Mag. (6) 49, 466 (1925).