Glossary of Ecology (6th ed.) by Krebs (2009)
- amount of usable material taken from a harvested population, measured in numbers or biomass.
"A Dictionary of Ecology, Evolution and Systematics (2nd ed.)" by Lincoln et al. (1998)
- That part of production utilized by a consumer species or by a group belonging to a higher trophic level, or by man.
- Krebs, C. J. 2009. Ecology, 6th ed. -xvi + 655 pp. Pearson Benjamin Cummings, San Francisco.
- Lincoln, R., Boxshall, G. & Clark, P. 1998. A Dictionary of Ecology, Evolution and Systematics. ix + 361 pp. Cambridge University Press, Cambridge.