| APA | SPO. (2012, February 15). In Acronym Geek. Retrieved 03:27, February 15, 2012, from http://www.acronymgeek.com/SPO |
| MLA | "SPO." Acronym Geek. (2012). Acronym Geek. 15 Feb 2012 <http://www.acronymgeek.com/SPO>. |
| MHRA | 'SPO', Acronym Geek, 15 February 2012, <http://www.acronymgeek.com/SPO> [accessed 15 February 2012] |
| Chicago | "SPO", http://www.acronymgeek.com/SPO (accessed February 15, 2012). |
| CBE/CSE | SPO [Internet]. Acronym Geek; 2012 Feb 15 [cited 2012 Feb 15]. Available from: http://www.acronymgeek.com/SPO. |
| Bluebook | SPO, http://www.acronymgeek.com/SPO (last visited February 15, 2012). |
| Bluebook: Harvard JOLT | See Acronym Geek, SPO, http://www.acronymgeek.com/SPO (optional description here) (as of Feb. 15, 2012, 03:27). |
| AMA | SPO. Acronym Geek. February 15, 2012, 03:27. Available at: http://www.acronymgeek.com/SPO. Accessed February 15, 2012, 03:27. |