| APA | Smart Define. (2013). hydrogen atom thesaurus. Retrieved September 21, 2026, from https://smartdefine.org/hydrogen_atom/thesaurus/narrower |
| Chicago | Smart Define. 2013. "hydrogen atom thesaurus" https://smartdefine.org/hydrogen_atom/thesaurus/narrower (accessed September 21, 2026). |
| Harvard | Smart Define 2013, hydrogen atom thesaurus, Smart Define, viewed 21 September, 2026, <https://smartdefine.org/hydrogen_atom/thesaurus/narrower>. |
| MLA | Smart Define. "hydrogen atom thesaurus" 18 May 2013. Web. 21 September 2026. <https://smartdefine.org/hydrogen_atom/thesaurus/narrower> |