Webster's Revised Unabridged Dictionary
| APA | Webster's. (2011). impugnation. Retrieved September 21, 2026, from http://smartdefine.org/impugnation/definitions/2019910 |
| Chicago | Webster's. 2011. "impugnation" http://smartdefine.org/impugnation/definitions/2019910 (accessed September 21, 2026). |
| Harvard | Webster's 2011, impugnation, Smart Define, viewed 21 September, 2026, <http://smartdefine.org/impugnation/definitions/2019910>. |
| MLA | Webster's. "impugnation" 27 May 2011. Web. 21 September 2026. <http://smartdefine.org/impugnation/definitions/2019910> |