| APA | Smart Define. (2015). stiffen thesaurus. Retrieved September 27, 2026, from https://smartdefine.org/stiffen/thesaurus/related |
| Chicago | Smart Define. 2015. "stiffen thesaurus" https://smartdefine.org/stiffen/thesaurus/related (accessed September 27, 2026). |
| Harvard | Smart Define 2015, stiffen thesaurus, Smart Define, viewed 27 September, 2026, <https://smartdefine.org/stiffen/thesaurus/related>. |
| MLA | Smart Define. "stiffen thesaurus" 13 April 2015. Web. 27 September 2026. <https://smartdefine.org/stiffen/thesaurus/related> |