| APA | Smart Define. (2015). niobium thesaurus. Retrieved September 25, 2026, from https://smartdefine.org/niobium/thesaurus/narrower |
| Chicago | Smart Define. 2015. "niobium thesaurus" https://smartdefine.org/niobium/thesaurus/narrower (accessed September 25, 2026). |
| Harvard | Smart Define 2015, niobium thesaurus, Smart Define, viewed 25 September, 2026, <https://smartdefine.org/niobium/thesaurus/narrower>. |
| MLA | Smart Define. "niobium thesaurus" 13 April 2015. Web. 25 September 2026. <https://smartdefine.org/niobium/thesaurus/narrower> |