Webster's Revised Unabridged Dictionary
| APA | Webster's. (2011). crup. Retrieved September 28, 2026, from http://smartdefine.org/crup/definitions/1993370 |
| Chicago | Webster's. 2011. "crup" http://smartdefine.org/crup/definitions/1993370 (accessed September 28, 2026). |
| Harvard | Webster's 2011, crup, Smart Define, viewed 28 September, 2026, <http://smartdefine.org/crup/definitions/1993370>. |
| MLA | Webster's. "crup" 27 May 2011. Web. 28 September 2026. <http://smartdefine.org/crup/definitions/1993370> |