| APA | Smart Define. (1970). eocene life of north america thesaurus. Retrieved September 30, 2026, from https://smartdefine.org/eocene_life_of_north_america/thesaurus/broader |
| Chicago | Smart Define. 1970. "eocene life of north america thesaurus" https://smartdefine.org/eocene_life_of_north_america/thesaurus/broader (accessed September 30, 2026). |
| Harvard | Smart Define 1970, eocene life of north america thesaurus, Smart Define, viewed 30 September, 2026, <https://smartdefine.org/eocene_life_of_north_america/thesaurus/broader>. |
| MLA | Smart Define. "eocene life of north america thesaurus" 1 January 1970. Web. 30 September 2026. <https://smartdefine.org/eocene_life_of_north_america/thesaurus/broader> |