| APA | ZPO. (2012, February 14). In Acronym Geek. Retrieved 11:27, February 14, 2012, from http://www.acronymgeek.com/ZPO |
| MLA | "ZPO." Acronym Geek. (2012). Acronym Geek. 14 Feb 2012 <http://www.acronymgeek.com/ZPO>. |
| MHRA | 'ZPO', Acronym Geek, 14 February 2012, <http://www.acronymgeek.com/ZPO> [accessed 14 February 2012] |
| Chicago | "ZPO", http://www.acronymgeek.com/ZPO (accessed February 14, 2012). |
| CBE/CSE | ZPO [Internet]. Acronym Geek; 2012 Feb 14 [cited 2012 Feb 14]. Available from: http://www.acronymgeek.com/ZPO. |
| Bluebook | ZPO, http://www.acronymgeek.com/ZPO (last visited February 14, 2012). |
| Bluebook: Harvard JOLT | See Acronym Geek, ZPO, http://www.acronymgeek.com/ZPO (optional description here) (as of Feb. 14, 2012, 11:27). |
| AMA | ZPO. Acronym Geek. February 14, 2012, 11:27. Available at: http://www.acronymgeek.com/ZPO. Accessed February 14, 2012, 11:27. |