| APA | Smart Define. (1970). Cretaceous-Tertiary boundary thesaurus. Retrieved September 24, 2026, from https://smartdefine.org/cretaceous-tertiary_boundary/thesaurus/synonyms |
| Chicago | Smart Define. 1970. "Cretaceous-Tertiary boundary thesaurus" https://smartdefine.org/cretaceous-tertiary_boundary/thesaurus/synonyms (accessed September 24, 2026). |
| Harvard | Smart Define 1970, Cretaceous-Tertiary boundary thesaurus, Smart Define, viewed 24 September, 2026, <https://smartdefine.org/cretaceous-tertiary_boundary/thesaurus/synonyms>. |
| MLA | Smart Define. "Cretaceous-Tertiary boundary thesaurus" 1 January 1970. Web. 24 September 2026. <https://smartdefine.org/cretaceous-tertiary_boundary/thesaurus/synonyms> |