| APA | Smart Define. (1970). a serious matter thesaurus. Retrieved September 26, 2026, from https://smartdefine.org/a_serious_matter/thesaurus/synonyms |
| Chicago | Smart Define. 1970. "a serious matter thesaurus" https://smartdefine.org/a_serious_matter/thesaurus/synonyms (accessed September 26, 2026). |
| Harvard | Smart Define 1970, a serious matter thesaurus, Smart Define, viewed 26 September, 2026, <https://smartdefine.org/a_serious_matter/thesaurus/synonyms>. |
| MLA | Smart Define. "a serious matter thesaurus" 1 January 1970. Web. 26 September 2026. <https://smartdefine.org/a_serious_matter/thesaurus/synonyms> |