| APA | Smart Define. (2013). letterless thesaurus. Retrieved September 22, 2026, from https://smartdefine.org/letterless/thesaurus/antonyms |
| Chicago | Smart Define. 2013. "letterless thesaurus" https://smartdefine.org/letterless/thesaurus/antonyms (accessed September 22, 2026). |
| Harvard | Smart Define 2013, letterless thesaurus, Smart Define, viewed 22 September, 2026, <https://smartdefine.org/letterless/thesaurus/antonyms>. |
| MLA | Smart Define. "letterless thesaurus" 19 May 2013. Web. 22 September 2026. <https://smartdefine.org/letterless/thesaurus/antonyms> |