| APA | PO. (2012, February 9). In Acronym Geek. Retrieved 13:53, February 9, 2012, from http://www.acronymgeek.com/PO |
| MLA | "PO." Acronym Geek. (2012). Acronym Geek. 9 Feb 2012 <http://www.acronymgeek.com/PO>. |
| MHRA | 'PO', Acronym Geek, 9 February 2012, <http://www.acronymgeek.com/PO> [accessed 9 February 2012] |
| Chicago | "PO", http://www.acronymgeek.com/PO (accessed February 9, 2012). |
| CBE/CSE | PO [Internet]. Acronym Geek; 2012 Feb 9 [cited 2012 Feb 9]. Available from: http://www.acronymgeek.com/PO. |
| Bluebook | PO, http://www.acronymgeek.com/PO (last visited February 9, 2012). |
| Bluebook: Harvard JOLT | See Acronym Geek, PO, http://www.acronymgeek.com/PO (optional description here) (as of Feb. 9, 2012, 13:53). |
| AMA | PO. Acronym Geek. February 9, 2012, 13:53. Available at: http://www.acronymgeek.com/PO. Accessed February 9, 2012, 13:53. |