| APA | OPOH. (2012, February 16). In Acronym Geek. Retrieved 20:33, February 16, 2012, from http://www.acronymgeek.com/OPOH |
| MLA | "OPOH." Acronym Geek. (2012). Acronym Geek. 16 Feb 2012 <http://www.acronymgeek.com/OPOH>. |
| MHRA | 'OPOH', Acronym Geek, 16 February 2012, <http://www.acronymgeek.com/OPOH> [accessed 16 February 2012] |
| Chicago | "OPOH", http://www.acronymgeek.com/OPOH (accessed February 16, 2012). |
| CBE/CSE | OPOH [Internet]. Acronym Geek; 2012 Feb 16 [cited 2012 Feb 16]. Available from: http://www.acronymgeek.com/OPOH. |
| Bluebook | OPOH, http://www.acronymgeek.com/OPOH (last visited February 16, 2012). |
| Bluebook: Harvard JOLT | See Acronym Geek, OPOH, http://www.acronymgeek.com/OPOH (optional description here) (as of Feb. 16, 2012, 20:33). |
| AMA | OPOH. Acronym Geek. February 16, 2012, 20:33. Available at: http://www.acronymgeek.com/OPOH. Accessed February 16, 2012, 20:33. |