| APA | Smart Define. (2013). actinium series thesaurus. Retrieved September 24, 2026, from https://smartdefine.org/actinium_series/thesaurus/synonyms |
| Chicago | Smart Define. 2013. "actinium series thesaurus" https://smartdefine.org/actinium_series/thesaurus/synonyms (accessed September 24, 2026). |
| Harvard | Smart Define 2013, actinium series thesaurus, Smart Define, viewed 24 September, 2026, <https://smartdefine.org/actinium_series/thesaurus/synonyms>. |
| MLA | Smart Define. "actinium series thesaurus" 17 May 2013. Web. 24 September 2026. <https://smartdefine.org/actinium_series/thesaurus/synonyms> |