| APA | IOU. (2012, February 8). In Acronym Geek. Retrieved 20:03, February 8, 2012, from http://www.acronymgeek.com/IOU |
| MLA | "IOU." Acronym Geek. (2012). Acronym Geek. 8 Feb 2012 <http://www.acronymgeek.com/IOU>. |
| MHRA | 'IOU', Acronym Geek, 8 February 2012, <http://www.acronymgeek.com/IOU> [accessed 8 February 2012] |
| Chicago | "IOU", http://www.acronymgeek.com/IOU (accessed February 8, 2012). |
| CBE/CSE | IOU [Internet]. Acronym Geek; 2012 Feb 8 [cited 2012 Feb 8]. Available from: http://www.acronymgeek.com/IOU. |
| Bluebook | IOU, http://www.acronymgeek.com/IOU (last visited February 8, 2012). |
| Bluebook: Harvard JOLT | See Acronym Geek, IOU, http://www.acronymgeek.com/IOU (optional description here) (as of Feb. 8, 2012, 20:03). |
| AMA | IOU. Acronym Geek. February 8, 2012, 20:03. Available at: http://www.acronymgeek.com/IOU. Accessed February 8, 2012, 20:03. |