| APA | Smart Define. (1970). volcano warning scheme of the United States thesaurus. Retrieved September 26, 2026, from https://smartdefine.org/volcano_warning_scheme_of_the_united_states/thesaurus/broader |
| Chicago | Smart Define. 1970. "volcano warning scheme of the United States thesaurus" https://smartdefine.org/volcano_warning_scheme_of_the_united_states/thesaurus/broader (accessed September 26, 2026). |
| Harvard | Smart Define 1970, volcano warning scheme of the United States thesaurus, Smart Define, viewed 26 September, 2026, <https://smartdefine.org/volcano_warning_scheme_of_the_united_states/thesaurus/broader>. |
| MLA | Smart Define. "volcano warning scheme of the United States thesaurus" 1 January 1970. Web. 26 September 2026. <https://smartdefine.org/volcano_warning_scheme_of_the_united_states/thesaurus/broader> |