| APA | Smart Define. (-0001). closed system thesaurus. Retrieved September 24, 2026, from https://smartdefine.org/closed_system/thesaurus/narrower |
| Chicago | Smart Define. -0001. "closed system thesaurus" https://smartdefine.org/closed_system/thesaurus/narrower (accessed September 24, 2026). |
| Harvard | Smart Define -0001, closed system thesaurus, Smart Define, viewed 24 September, 2026, <https://smartdefine.org/closed_system/thesaurus/narrower>. |
| MLA | Smart Define. "closed system thesaurus" 30 November -0001. Web. 24 September 2026. <https://smartdefine.org/closed_system/thesaurus/narrower> |