| APA | O. (2012, February 12). In Acronym Geek. Retrieved 07:27, February 12, 2012, from http://www.acronymgeek.com/O |
| MLA | "O." Acronym Geek. (2012). Acronym Geek. 12 Feb 2012 <http://www.acronymgeek.com/O>. |
| MHRA | 'O', Acronym Geek, 12 February 2012, <http://www.acronymgeek.com/O> [accessed 12 February 2012] |
| Chicago | "O", http://www.acronymgeek.com/O (accessed February 12, 2012). |
| CBE/CSE | O [Internet]. Acronym Geek; 2012 Feb 12 [cited 2012 Feb 12]. Available from: http://www.acronymgeek.com/O. |
| Bluebook | O, http://www.acronymgeek.com/O (last visited February 12, 2012). |
| Bluebook: Harvard JOLT | See Acronym Geek, O, http://www.acronymgeek.com/O (optional description here) (as of Feb. 12, 2012, 07:27). |
| AMA | O. Acronym Geek. February 12, 2012, 07:27. Available at: http://www.acronymgeek.com/O. Accessed February 12, 2012, 07:27. |