| APA | Smart Define. (2013). parts per million thesaurus. Retrieved October 1, 2026, from https://smartdefine.org/parts_per_million/thesaurus/related |
| Chicago | Smart Define. 2013. "parts per million thesaurus" https://smartdefine.org/parts_per_million/thesaurus/related (accessed October 1, 2026). |
| Harvard | Smart Define 2013, parts per million thesaurus, Smart Define, viewed 1 October, 2026, <https://smartdefine.org/parts_per_million/thesaurus/related>. |
| MLA | Smart Define. "parts per million thesaurus" 18 May 2013. Web. 1 October 2026. <https://smartdefine.org/parts_per_million/thesaurus/related> |