| APA | Smart Define. (2011). exchange of letters thesaurus. Retrieved September 26, 2026, from https://smartdefine.org/exchange_of_letters/thesaurus/narrower |
| Chicago | Smart Define. 2011. "exchange of letters thesaurus" https://smartdefine.org/exchange_of_letters/thesaurus/narrower (accessed September 26, 2026). |
| Harvard | Smart Define 2011, exchange of letters thesaurus, Smart Define, viewed 26 September, 2026, <https://smartdefine.org/exchange_of_letters/thesaurus/narrower>. |
| MLA | Smart Define. "exchange of letters thesaurus" 20 May 2011. Web. 26 September 2026. <https://smartdefine.org/exchange_of_letters/thesaurus/narrower> |