| APA | Smart Define. (2011). expanse of the heavens thesaurus. Retrieved September 26, 2026, from https://smartdefine.org/expanse_of_the_heavens/thesaurus/narrower |
| Chicago | Smart Define. 2011. "expanse of the heavens thesaurus" https://smartdefine.org/expanse_of_the_heavens/thesaurus/narrower (accessed September 26, 2026). |
| Harvard | Smart Define 2011, expanse of the heavens thesaurus, Smart Define, viewed 26 September, 2026, <https://smartdefine.org/expanse_of_the_heavens/thesaurus/narrower>. |
| MLA | Smart Define. "expanse of the heavens thesaurus" 2 May 2011. Web. 26 September 2026. <https://smartdefine.org/expanse_of_the_heavens/thesaurus/narrower> |