| APA | Smart Define. (2013). spiff up thesaurus. Retrieved September 21, 2026, from https://smartdefine.org/spiff_up/thesaurus/antonyms |
| Chicago | Smart Define. 2013. "spiff up thesaurus" https://smartdefine.org/spiff_up/thesaurus/antonyms (accessed September 21, 2026). |
| Harvard | Smart Define 2013, spiff up thesaurus, Smart Define, viewed 21 September, 2026, <https://smartdefine.org/spiff_up/thesaurus/antonyms>. |
| MLA | Smart Define. "spiff up thesaurus" 18 May 2013. Web. 21 September 2026. <https://smartdefine.org/spiff_up/thesaurus/antonyms> |