| APA | Smart Define. (2011). acoustic spectrum thesaurus. Retrieved September 26, 2026, from https://smartdefine.org/acoustic_spectrum/thesaurus/narrower |
| Chicago | Smart Define. 2011. "acoustic spectrum thesaurus" https://smartdefine.org/acoustic_spectrum/thesaurus/narrower (accessed September 26, 2026). |
| Harvard | Smart Define 2011, acoustic spectrum thesaurus, Smart Define, viewed 26 September, 2026, <https://smartdefine.org/acoustic_spectrum/thesaurus/narrower>. |
| MLA | Smart Define. "acoustic spectrum thesaurus" 26 April 2011. Web. 26 September 2026. <https://smartdefine.org/acoustic_spectrum/thesaurus/narrower> |