| APA | O. (2012, February 9). In Acronym Geek. Retrieved 15:36, February 9, 2012, from http://www.acronymgeek.com/O |
| MLA | "O." Acronym Geek. (2012). Acronym Geek. 9 Feb 2012 <http://www.acronymgeek.com/O>. |
| MHRA | 'O', Acronym Geek, 9 February 2012, <http://www.acronymgeek.com/O> [accessed 9 February 2012] |
| Chicago | "O", http://www.acronymgeek.com/O (accessed February 9, 2012). |
| CBE/CSE | O [Internet]. Acronym Geek; 2012 Feb 9 [cited 2012 Feb 9]. Available from: http://www.acronymgeek.com/O. |
| Bluebook | O, http://www.acronymgeek.com/O (last visited February 9, 2012). |
| Bluebook: Harvard JOLT | See Acronym Geek, O, http://www.acronymgeek.com/O (optional description here) (as of Feb. 9, 2012, 15:36). |
| AMA | O. Acronym Geek. February 9, 2012, 15:36. Available at: http://www.acronymgeek.com/O. Accessed February 9, 2012, 15:36. |