| APA | OPOE. (2012, February 15). In Acronym Geek. Retrieved 18:45, February 15, 2012, from http://www.acronymgeek.com/OPOE |
| MLA | "OPOE." Acronym Geek. (2012). Acronym Geek. 15 Feb 2012 <http://www.acronymgeek.com/OPOE>. |
| MHRA | 'OPOE', Acronym Geek, 15 February 2012, <http://www.acronymgeek.com/OPOE> [accessed 15 February 2012] |
| Chicago | "OPOE", http://www.acronymgeek.com/OPOE (accessed February 15, 2012). |
| CBE/CSE | OPOE [Internet]. Acronym Geek; 2012 Feb 15 [cited 2012 Feb 15]. Available from: http://www.acronymgeek.com/OPOE. |
| Bluebook | OPOE, http://www.acronymgeek.com/OPOE (last visited February 15, 2012). |
| Bluebook: Harvard JOLT | See Acronym Geek, OPOE, http://www.acronymgeek.com/OPOE (optional description here) (as of Feb. 15, 2012, 18:45). |
| AMA | OPOE. Acronym Geek. February 15, 2012, 18:45. Available at: http://www.acronymgeek.com/OPOE. Accessed February 15, 2012, 18:45. |