| APA | Smart Define. (2016). serious thesaurus. Retrieved September 21, 2026, from https://smartdefine.org/serious/thesaurus/narrower |
| Chicago | Smart Define. 2016. "serious thesaurus" https://smartdefine.org/serious/thesaurus/narrower (accessed September 21, 2026). |
| Harvard | Smart Define 2016, serious thesaurus, Smart Define, viewed 21 September, 2026, <https://smartdefine.org/serious/thesaurus/narrower>. |
| MLA | Smart Define. "serious thesaurus" 24 February 2016. Web. 21 September 2026. <https://smartdefine.org/serious/thesaurus/narrower> |