| APA | Smart Define. (1970). spaceflight concept thesaurus. Retrieved September 20, 2026, from https://smartdefine.org/spaceflight_concept/thesaurus/narrower |
| Chicago | Smart Define. 1970. "spaceflight concept thesaurus" https://smartdefine.org/spaceflight_concept/thesaurus/narrower (accessed September 20, 2026). |
| Harvard | Smart Define 1970, spaceflight concept thesaurus, Smart Define, viewed 20 September, 2026, <https://smartdefine.org/spaceflight_concept/thesaurus/narrower>. |
| MLA | Smart Define. "spaceflight concept thesaurus" 1 January 1970. Web. 20 September 2026. <https://smartdefine.org/spaceflight_concept/thesaurus/narrower> |