1. Miller, G. S. Catalogue of the Mammals of Western Europe (British Museum of Natural History, London, 1912).
2. Degerbøl, M. Proc. prehist. Soc. 3, 35–55 (1961).
3. Lawrence, B. Z. Saugetierkd. 32, 44–59 (1967).
4. Scott, J. P. Evol. Biol. 2, 243–275 (1968).
5. Simonsen, V. Hereditas 82, 7–18 (1976).