| APA | Smart Define. (1970). twenty-first century steam thesaurus. Retrieved October 1, 2026, from https://smartdefine.org/twenty-first_century_steam/thesaurus/broader |
| Chicago | Smart Define. 1970. "twenty-first century steam thesaurus" https://smartdefine.org/twenty-first_century_steam/thesaurus/broader (accessed October 1, 2026). |
| Harvard | Smart Define 1970, twenty-first century steam thesaurus, Smart Define, viewed 1 October, 2026, <https://smartdefine.org/twenty-first_century_steam/thesaurus/broader>. |
| MLA | Smart Define. "twenty-first century steam thesaurus" 1 January 1970. Web. 1 October 2026. <https://smartdefine.org/twenty-first_century_steam/thesaurus/broader> |