| APA | Smart Define. (2013). in difficulty thesaurus. Retrieved September 23, 2026, from https://smartdefine.org/in_difficulty/thesaurus/related |
| Chicago | Smart Define. 2013. "in difficulty thesaurus" https://smartdefine.org/in_difficulty/thesaurus/related (accessed September 23, 2026). |
| Harvard | Smart Define 2013, in difficulty thesaurus, Smart Define, viewed 23 September, 2026, <https://smartdefine.org/in_difficulty/thesaurus/related>. |
| MLA | Smart Define. "in difficulty thesaurus" 19 May 2013. Web. 23 September 2026. <https://smartdefine.org/in_difficulty/thesaurus/related> |