| APA | DAY-OPU. (2012, February 12). In Acronym Geek. Retrieved 09:27, February 12, 2012, from http://www.acronymgeek.com/DAY-OPU |
| MLA | "DAY-OPU." Acronym Geek. (2012). Acronym Geek. 12 Feb 2012 <http://www.acronymgeek.com/DAY-OPU>. |
| MHRA | 'DAY-OPU', Acronym Geek, 12 February 2012, <http://www.acronymgeek.com/DAY-OPU> [accessed 12 February 2012] |
| Chicago | "DAY-OPU", http://www.acronymgeek.com/DAY-OPU (accessed February 12, 2012). |
| CBE/CSE | DAY-OPU [Internet]. Acronym Geek; 2012 Feb 12 [cited 2012 Feb 12]. Available from: http://www.acronymgeek.com/DAY-OPU. |
| Bluebook | DAY-OPU, http://www.acronymgeek.com/DAY-OPU (last visited February 12, 2012). |
| Bluebook: Harvard JOLT | See Acronym Geek, DAY-OPU, http://www.acronymgeek.com/DAY-OPU (optional description here) (as of Feb. 12, 2012, 09:27). |
| AMA | DAY-OPU. Acronym Geek. February 12, 2012, 09:27. Available at: http://www.acronymgeek.com/DAY-OPU. Accessed February 12, 2012, 09:27. |