| APA | OPUD. (2012, February 15). In Acronym Geek. Retrieved 05:22, February 15, 2012, from http://www.acronymgeek.com/OPUD |
| MLA | "OPUD." Acronym Geek. (2012). Acronym Geek. 15 Feb 2012 <http://www.acronymgeek.com/OPUD>. |
| MHRA | 'OPUD', Acronym Geek, 15 February 2012, <http://www.acronymgeek.com/OPUD> [accessed 15 February 2012] |
| Chicago | "OPUD", http://www.acronymgeek.com/OPUD (accessed February 15, 2012). |
| CBE/CSE | OPUD [Internet]. Acronym Geek; 2012 Feb 15 [cited 2012 Feb 15]. Available from: http://www.acronymgeek.com/OPUD. |
| Bluebook | OPUD, http://www.acronymgeek.com/OPUD (last visited February 15, 2012). |
| Bluebook: Harvard JOLT | See Acronym Geek, OPUD, http://www.acronymgeek.com/OPUD (optional description here) (as of Feb. 15, 2012, 05:22). |
| AMA | OPUD. Acronym Geek. February 15, 2012, 05:22. Available at: http://www.acronymgeek.com/OPUD. Accessed February 15, 2012, 05:22. |