| APA | Smart Define. (2011). survival of the fittest thesaurus. Retrieved September 30, 2026, from https://smartdefine.org/survival_of_the_fittest/thesaurus/broader |
| Chicago | Smart Define. 2011. "survival of the fittest thesaurus" https://smartdefine.org/survival_of_the_fittest/thesaurus/broader (accessed September 30, 2026). |
| Harvard | Smart Define 2011, survival of the fittest thesaurus, Smart Define, viewed 30 September, 2026, <https://smartdefine.org/survival_of_the_fittest/thesaurus/broader>. |
| MLA | Smart Define. "survival of the fittest thesaurus" 24 May 2011. Web. 30 September 2026. <https://smartdefine.org/survival_of_the_fittest/thesaurus/broader> |