| APA | SOPO. (2012, February 15). In Acronym Geek. Retrieved 12:25, February 15, 2012, from http://www.acronymgeek.com/SOPO |
| MLA | "SOPO." Acronym Geek. (2012). Acronym Geek. 15 Feb 2012 <http://www.acronymgeek.com/SOPO>. |
| MHRA | 'SOPO', Acronym Geek, 15 February 2012, <http://www.acronymgeek.com/SOPO> [accessed 15 February 2012] |
| Chicago | "SOPO", http://www.acronymgeek.com/SOPO (accessed February 15, 2012). |
| CBE/CSE | SOPO [Internet]. Acronym Geek; 2012 Feb 15 [cited 2012 Feb 15]. Available from: http://www.acronymgeek.com/SOPO. |
| Bluebook | SOPO, http://www.acronymgeek.com/SOPO (last visited February 15, 2012). |
| Bluebook: Harvard JOLT | See Acronym Geek, SOPO, http://www.acronymgeek.com/SOPO (optional description here) (as of Feb. 15, 2012, 12:25). |
| AMA | SOPO. Acronym Geek. February 15, 2012, 12:25. Available at: http://www.acronymgeek.com/SOPO. Accessed February 15, 2012, 12:25. |