| APA | Smart Define. (2015). heart of oak thesaurus. Retrieved September 26, 2026, from https://smartdefine.org/heart_of_oak/thesaurus/narrower |
| Chicago | Smart Define. 2015. "heart of oak thesaurus" https://smartdefine.org/heart_of_oak/thesaurus/narrower (accessed September 26, 2026). |
| Harvard | Smart Define 2015, heart of oak thesaurus, Smart Define, viewed 26 September, 2026, <https://smartdefine.org/heart_of_oak/thesaurus/narrower>. |
| MLA | Smart Define. "heart of oak thesaurus" 10 April 2015. Web. 26 September 2026. <https://smartdefine.org/heart_of_oak/thesaurus/narrower> |