| APA | Smart Define. (2016). black as coal thesaurus. Retrieved September 20, 2026, from https://smartdefine.org/black_as_coal/thesaurus/synonyms |
| Chicago | Smart Define. 2016. "black as coal thesaurus" https://smartdefine.org/black_as_coal/thesaurus/synonyms (accessed September 20, 2026). |
| Harvard | Smart Define 2016, black as coal thesaurus, Smart Define, viewed 20 September, 2026, <https://smartdefine.org/black_as_coal/thesaurus/synonyms>. |
| MLA | Smart Define. "black as coal thesaurus" 8 March 2016. Web. 20 September 2026. <https://smartdefine.org/black_as_coal/thesaurus/synonyms> |