| APA | IO. (2012, February 14). In Acronym Geek. Retrieved 06:49, February 14, 2012, from http://www.acronymgeek.com/IO |
| MLA | "IO." Acronym Geek. (2012). Acronym Geek. 14 Feb 2012 <http://www.acronymgeek.com/IO>. |
| MHRA | 'IO', Acronym Geek, 14 February 2012, <http://www.acronymgeek.com/IO> [accessed 14 February 2012] |
| Chicago | "IO", http://www.acronymgeek.com/IO (accessed February 14, 2012). |
| CBE/CSE | IO [Internet]. Acronym Geek; 2012 Feb 14 [cited 2012 Feb 14]. Available from: http://www.acronymgeek.com/IO. |
| Bluebook | IO, http://www.acronymgeek.com/IO (last visited February 14, 2012). |
| Bluebook: Harvard JOLT | See Acronym Geek, IO, http://www.acronymgeek.com/IO (optional description here) (as of Feb. 14, 2012, 06:49). |
| AMA | IO. Acronym Geek. February 14, 2012, 06:49. Available at: http://www.acronymgeek.com/IO. Accessed February 14, 2012, 06:49. |