| APA | Smart Define. (2015). labor in vain thesaurus. Retrieved September 29, 2026, from https://smartdefine.org/labor_in_vain/thesaurus/synonyms |
| Chicago | Smart Define. 2015. "labor in vain thesaurus" https://smartdefine.org/labor_in_vain/thesaurus/synonyms (accessed September 29, 2026). |
| Harvard | Smart Define 2015, labor in vain thesaurus, Smart Define, viewed 29 September, 2026, <https://smartdefine.org/labor_in_vain/thesaurus/synonyms>. |
| MLA | Smart Define. "labor in vain thesaurus" 14 April 2015. Web. 29 September 2026. <https://smartdefine.org/labor_in_vain/thesaurus/synonyms> |