| APA | Smart Define. (2013). concave shape thesaurus. Retrieved September 20, 2026, from https://smartdefine.org/concave_shape/thesaurus/narrower |
| Chicago | Smart Define. 2013. "concave shape thesaurus" https://smartdefine.org/concave_shape/thesaurus/narrower (accessed September 20, 2026). |
| Harvard | Smart Define 2013, concave shape thesaurus, Smart Define, viewed 20 September, 2026, <https://smartdefine.org/concave_shape/thesaurus/narrower>. |
| MLA | Smart Define. "concave shape thesaurus" 18 May 2013. Web. 20 September 2026. <https://smartdefine.org/concave_shape/thesaurus/narrower> |