| APA | Smart Define. (2015). hardheadedness thesaurus. Retrieved September 24, 2026, from https://smartdefine.org/hardheadedness/thesaurus/related |
| Chicago | Smart Define. 2015. "hardheadedness thesaurus" https://smartdefine.org/hardheadedness/thesaurus/related (accessed September 24, 2026). |
| Harvard | Smart Define 2015, hardheadedness thesaurus, Smart Define, viewed 24 September, 2026, <https://smartdefine.org/hardheadedness/thesaurus/related>. |
| MLA | Smart Define. "hardheadedness thesaurus" 14 April 2015. Web. 24 September 2026. <https://smartdefine.org/hardheadedness/thesaurus/related> |