| APA | O/P. (2012, February 10). In Acronym Geek. Retrieved 13:15, February 10, 2012, from http://www.acronymgeek.com/O/P |
| MLA | "O/P." Acronym Geek. (2012). Acronym Geek. 10 Feb 2012 <http://www.acronymgeek.com/O/P>. |
| MHRA | 'O/P', Acronym Geek, 10 February 2012, <http://www.acronymgeek.com/O/P> [accessed 10 February 2012] |
| Chicago | "O/P", http://www.acronymgeek.com/O/P (accessed February 10, 2012). |
| CBE/CSE | O/P [Internet]. Acronym Geek; 2012 Feb 10 [cited 2012 Feb 10]. Available from: http://www.acronymgeek.com/O/P. |
| Bluebook | O/P, http://www.acronymgeek.com/O/P (last visited February 10, 2012). |
| Bluebook: Harvard JOLT | See Acronym Geek, O/P, http://www.acronymgeek.com/O/P (optional description here) (as of Feb. 10, 2012, 13:15). |
| AMA | O/P. Acronym Geek. February 10, 2012, 13:15. Available at: http://www.acronymgeek.com/O/P. Accessed February 10, 2012, 13:15. |