| APA | OPUL. (2012, February 15). In Acronym Geek. Retrieved 05:40, February 15, 2012, from http://www.acronymgeek.com/OPUL |
| MLA | "OPUL." Acronym Geek. (2012). Acronym Geek. 15 Feb 2012 <http://www.acronymgeek.com/OPUL>. |
| MHRA | 'OPUL', Acronym Geek, 15 February 2012, <http://www.acronymgeek.com/OPUL> [accessed 15 February 2012] |
| Chicago | "OPUL", http://www.acronymgeek.com/OPUL (accessed February 15, 2012). |
| CBE/CSE | OPUL [Internet]. Acronym Geek; 2012 Feb 15 [cited 2012 Feb 15]. Available from: http://www.acronymgeek.com/OPUL. |
| Bluebook | OPUL, http://www.acronymgeek.com/OPUL (last visited February 15, 2012). |
| Bluebook: Harvard JOLT | See Acronym Geek, OPUL, http://www.acronymgeek.com/OPUL (optional description here) (as of Feb. 15, 2012, 05:40). |
| AMA | OPUL. Acronym Geek. February 15, 2012, 05:40. Available at: http://www.acronymgeek.com/OPUL. Accessed February 15, 2012, 05:40. |