| APA | Smart Define. (1970). cretaceous-paleogene boundary thesaurus. Retrieved September 23, 2026, from https://smartdefine.org/cretaceous-paleogene_boundary/thesaurus/synonyms |
| Chicago | Smart Define. 1970. "cretaceous-paleogene boundary thesaurus" https://smartdefine.org/cretaceous-paleogene_boundary/thesaurus/synonyms (accessed September 23, 2026). |
| Harvard | Smart Define 1970, cretaceous-paleogene boundary thesaurus, Smart Define, viewed 23 September, 2026, <https://smartdefine.org/cretaceous-paleogene_boundary/thesaurus/synonyms>. |
| MLA | Smart Define. "cretaceous-paleogene boundary thesaurus" 1 January 1970. Web. 23 September 2026. <https://smartdefine.org/cretaceous-paleogene_boundary/thesaurus/synonyms> |