Glossary of Ecology (6th ed.) by Krebs (2009)
- particular truth of the natural world. Philosophers endlessly discuss what a fact is. Ecologists make observations, which may be faulty; consequently, every observation is not automatically a fact.
Glossary of "Environmental Science: Earth as a Living Planet (2nd ed.)" by Botkin & Keller (1998)
- Something the is known based on actual experience and observation.
- Botkin, D. B. & Keller, E. A. 1998. Environmental Science: Earth as a Living Planet, 2nd ed. -xxxxii + 649 pp. John Wiley & Sons, Inc., New York.