| APA | Smart Define. (2011). butanoic acid thesaurus. Retrieved September 28, 2026, from https://smartdefine.org/butanoic_acid/thesaurus/narrower |
| Chicago | Smart Define. 2011. "butanoic acid thesaurus" https://smartdefine.org/butanoic_acid/thesaurus/narrower (accessed September 28, 2026). |
| Harvard | Smart Define 2011, butanoic acid thesaurus, Smart Define, viewed 28 September, 2026, <https://smartdefine.org/butanoic_acid/thesaurus/narrower>. |
| MLA | Smart Define. "butanoic acid thesaurus" 26 April 2011. Web. 28 September 2026. <https://smartdefine.org/butanoic_acid/thesaurus/narrower> |