| APA | Smart Define. (1970). morning astronomical twilight thesaurus. Retrieved September 26, 2026, from https://smartdefine.org/morning_astronomical_twilight/thesaurus/broader |
| Chicago | Smart Define. 1970. "morning astronomical twilight thesaurus" https://smartdefine.org/morning_astronomical_twilight/thesaurus/broader (accessed September 26, 2026). |
| Harvard | Smart Define 1970, morning astronomical twilight thesaurus, Smart Define, viewed 26 September, 2026, <https://smartdefine.org/morning_astronomical_twilight/thesaurus/broader>. |
| MLA | Smart Define. "morning astronomical twilight thesaurus" 1 January 1970. Web. 26 September 2026. <https://smartdefine.org/morning_astronomical_twilight/thesaurus/broader> |