| APA | OPXS. (2012, February 17). In Acronym Geek. Retrieved 04:53, February 17, 2012, from http://www.acronymgeek.com/OPXS |
| MLA | "OPXS." Acronym Geek. (2012). Acronym Geek. 17 Feb 2012 <http://www.acronymgeek.com/OPXS>. |
| MHRA | 'OPXS', Acronym Geek, 17 February 2012, <http://www.acronymgeek.com/OPXS> [accessed 17 February 2012] |
| Chicago | "OPXS", http://www.acronymgeek.com/OPXS (accessed February 17, 2012). |
| CBE/CSE | OPXS [Internet]. Acronym Geek; 2012 Feb 17 [cited 2012 Feb 17]. Available from: http://www.acronymgeek.com/OPXS. |
| Bluebook | OPXS, http://www.acronymgeek.com/OPXS (last visited February 17, 2012). |
| Bluebook: Harvard JOLT | See Acronym Geek, OPXS, http://www.acronymgeek.com/OPXS (optional description here) (as of Feb. 17, 2012, 04:53). |
| AMA | OPXS. Acronym Geek. February 17, 2012, 04:53. Available at: http://www.acronymgeek.com/OPXS. Accessed February 17, 2012, 04:53. |