| APA | Smart Define. (2013). birken thesaurus. Retrieved September 20, 2026, from https://smartdefine.org/birken/thesaurus/synonyms |
| Chicago | Smart Define. 2013. "birken thesaurus" https://smartdefine.org/birken/thesaurus/synonyms (accessed September 20, 2026). |
| Harvard | Smart Define 2013, birken thesaurus, Smart Define, viewed 20 September, 2026, <https://smartdefine.org/birken/thesaurus/synonyms>. |
| MLA | Smart Define. "birken thesaurus" 28 June 2013. Web. 20 September 2026. <https://smartdefine.org/birken/thesaurus/synonyms> |