| APA | Smart Define. (2016). halcyon thesaurus. Retrieved September 24, 2026, from https://smartdefine.org/halcyon/thesaurus/antonyms |
| Chicago | Smart Define. 2016. "halcyon thesaurus" https://smartdefine.org/halcyon/thesaurus/antonyms (accessed September 24, 2026). |
| Harvard | Smart Define 2016, halcyon thesaurus, Smart Define, viewed 24 September, 2026, <https://smartdefine.org/halcyon/thesaurus/antonyms>. |
| MLA | Smart Define. "halcyon thesaurus" 29 February 2016. Web. 24 September 2026. <https://smartdefine.org/halcyon/thesaurus/antonyms> |