| APA | Smart Define. (2015). toughness thesaurus. Retrieved September 29, 2026, from https://smartdefine.org/toughness/thesaurus/related |
| Chicago | Smart Define. 2015. "toughness thesaurus" https://smartdefine.org/toughness/thesaurus/related (accessed September 29, 2026). |
| Harvard | Smart Define 2015, toughness thesaurus, Smart Define, viewed 29 September, 2026, <https://smartdefine.org/toughness/thesaurus/related>. |
| MLA | Smart Define. "toughness thesaurus" 21 December 2015. Web. 29 September 2026. <https://smartdefine.org/toughness/thesaurus/related> |