| APA | Smart Define. (1970). environmentally-clean thesaurus. Retrieved September 25, 2026, from https://smartdefine.org/environmentally-clean/thesaurus/synonyms |
| Chicago | Smart Define. 1970. "environmentally-clean thesaurus" https://smartdefine.org/environmentally-clean/thesaurus/synonyms (accessed September 25, 2026). |
| Harvard | Smart Define 1970, environmentally-clean thesaurus, Smart Define, viewed 25 September, 2026, <https://smartdefine.org/environmentally-clean/thesaurus/synonyms>. |
| MLA | Smart Define. "environmentally-clean thesaurus" 1 January 1970. Web. 25 September 2026. <https://smartdefine.org/environmentally-clean/thesaurus/synonyms> |