| APA | Smart Define. (1970). study of the earth thesaurus. Retrieved September 25, 2026, from https://smartdefine.org/study_of_the_earth/thesaurus/narrower |
| Chicago | Smart Define. 1970. "study of the earth thesaurus" https://smartdefine.org/study_of_the_earth/thesaurus/narrower (accessed September 25, 2026). |
| Harvard | Smart Define 1970, study of the earth thesaurus, Smart Define, viewed 25 September, 2026, <https://smartdefine.org/study_of_the_earth/thesaurus/narrower>. |
| MLA | Smart Define. "study of the earth thesaurus" 1 January 1970. Web. 25 September 2026. <https://smartdefine.org/study_of_the_earth/thesaurus/narrower> |