| APA | P-O. (2012, February 14). In Acronym Geek. Retrieved 09:38, February 14, 2012, from http://www.acronymgeek.com/P-O |
| MLA | "P-O." Acronym Geek. (2012). Acronym Geek. 14 Feb 2012 <http://www.acronymgeek.com/P-O>. |
| MHRA | 'P-O', Acronym Geek, 14 February 2012, <http://www.acronymgeek.com/P-O> [accessed 14 February 2012] |
| Chicago | "P-O", http://www.acronymgeek.com/P-O (accessed February 14, 2012). |
| CBE/CSE | P-O [Internet]. Acronym Geek; 2012 Feb 14 [cited 2012 Feb 14]. Available from: http://www.acronymgeek.com/P-O. |
| Bluebook | P-O, http://www.acronymgeek.com/P-O (last visited February 14, 2012). |
| Bluebook: Harvard JOLT | See Acronym Geek, P-O, http://www.acronymgeek.com/P-O (optional description here) (as of Feb. 14, 2012, 09:38). |
| AMA | P-O. Acronym Geek. February 14, 2012, 09:38. Available at: http://www.acronymgeek.com/P-O. Accessed February 14, 2012, 09:38. |