1. Hjort, J. Rapp. Conserv. Explor. Mer 20, 1–228 (1914).
2. Cushing, D. H. in Sea Fisheries Research (ed. Harden Jones, F. R.) 399–412 (Elek Science, London, 1974).
3. Cushing, D. H. Adv. Mar. Biol. 26, 249–294 (1990).
4. Sverdrup, H. U. J. Conseil Perm. Int. Explor. Mer 18, 287–295 (1953).
5. Platt, T. & Sathyendranath, S. Int. Coun. Explor. Sea CM O:3 (1996).