| APA | Smart Define. (2011). spear thistle thesaurus. Retrieved September 24, 2026, from https://smartdefine.org/spear_thistle/thesaurus/synonyms |
| Chicago | Smart Define. 2011. "spear thistle thesaurus" https://smartdefine.org/spear_thistle/thesaurus/synonyms (accessed September 24, 2026). |
| Harvard | Smart Define 2011, spear thistle thesaurus, Smart Define, viewed 24 September, 2026, <https://smartdefine.org/spear_thistle/thesaurus/synonyms>. |
| MLA | Smart Define. "spear thistle thesaurus" 26 April 2011. Web. 24 September 2026. <https://smartdefine.org/spear_thistle/thesaurus/synonyms> |