1. Good, R. New Phytol. 30, 149–171 (1931).
2. Cain, S. A. Foundation of Plant Geography (Harper, New York, 1944).
3. Pigott, C. D. in The Flora of a Changing Britain (ed. Perring, F. H.) 32–44 (Botanical Society of the British Isles & Classey, Hampton, 1970).
4. Salisbury, E. J. Geogrl J. 57, 312–335 (1926).
5. Iversen, J. Geol För. Stockh. Förh. 66, 463–483 (1944).