| APA | Smart Define. (2011). survival of the fittest thesaurus. Retrieved October 1, 2026, from https://smartdefine.org/survival_of_the_fittest/thesaurus/synonyms |
| Chicago | Smart Define. 2011. "survival of the fittest thesaurus" https://smartdefine.org/survival_of_the_fittest/thesaurus/synonyms (accessed October 1, 2026). |
| Harvard | Smart Define 2011, survival of the fittest thesaurus, Smart Define, viewed 1 October, 2026, <https://smartdefine.org/survival_of_the_fittest/thesaurus/synonyms>. |
| MLA | Smart Define. "survival of the fittest thesaurus" 24 May 2011. Web. 1 October 2026. <https://smartdefine.org/survival_of_the_fittest/thesaurus/synonyms> |