| APA | Smart Define. (2015). hard of heart thesaurus. Retrieved September 21, 2026, from https://smartdefine.org/hard_of_heart/thesaurus/synonyms |
| Chicago | Smart Define. 2015. "hard of heart thesaurus" https://smartdefine.org/hard_of_heart/thesaurus/synonyms (accessed September 21, 2026). |
| Harvard | Smart Define 2015, hard of heart thesaurus, Smart Define, viewed 21 September, 2026, <https://smartdefine.org/hard_of_heart/thesaurus/synonyms>. |
| MLA | Smart Define. "hard of heart thesaurus" 14 April 2015. Web. 21 September 2026. <https://smartdefine.org/hard_of_heart/thesaurus/synonyms> |