Glossary of "Life (9th ed.)" by Sadava et al. (2011)
- The state of inactivity of some animals during winter; marked by a drop in body temperature and metabolic rate.
- Sadava, D., Hillis, D. M., Heller, H. C. & Berenbaum, M. R. 2011. Life: The Science of Biology, 9th ed. -xliv + 1266 pp. Sinauer Associates, Inc., Sunderland.