| APA | Smart Define. (2015). piece of material thesaurus. Retrieved September 25, 2026, from https://smartdefine.org/piece_of_material/thesaurus/narrower |
| Chicago | Smart Define. 2015. "piece of material thesaurus" https://smartdefine.org/piece_of_material/thesaurus/narrower (accessed September 25, 2026). |
| Harvard | Smart Define 2015, piece of material thesaurus, Smart Define, viewed 25 September, 2026, <https://smartdefine.org/piece_of_material/thesaurus/narrower>. |
| MLA | Smart Define. "piece of material thesaurus" 10 April 2015. Web. 25 September 2026. <https://smartdefine.org/piece_of_material/thesaurus/narrower> |