| APA | Smart Define. (2011). hard to forget thesaurus. Retrieved September 20, 2026, from https://smartdefine.org/hard_to_forget/thesaurus/narrower |
| Chicago | Smart Define. 2011. "hard to forget thesaurus" https://smartdefine.org/hard_to_forget/thesaurus/narrower (accessed September 20, 2026). |
| Harvard | Smart Define 2011, hard to forget thesaurus, Smart Define, viewed 20 September, 2026, <https://smartdefine.org/hard_to_forget/thesaurus/narrower>. |
| MLA | Smart Define. "hard to forget thesaurus" 2 May 2011. Web. 20 September 2026. <https://smartdefine.org/hard_to_forget/thesaurus/narrower> |