| APA | OPUS. (2012, February 15). In Acronym Geek. Retrieved 16:49, February 15, 2012, from http://www.acronymgeek.com/OPUS |
| MLA | "OPUS." Acronym Geek. (2012). Acronym Geek. 15 Feb 2012 <http://www.acronymgeek.com/OPUS>. |
| MHRA | 'OPUS', Acronym Geek, 15 February 2012, <http://www.acronymgeek.com/OPUS> [accessed 15 February 2012] |
| Chicago | "OPUS", http://www.acronymgeek.com/OPUS (accessed February 15, 2012). |
| CBE/CSE | OPUS [Internet]. Acronym Geek; 2012 Feb 15 [cited 2012 Feb 15]. Available from: http://www.acronymgeek.com/OPUS. |
| Bluebook | OPUS, http://www.acronymgeek.com/OPUS (last visited February 15, 2012). |
| Bluebook: Harvard JOLT | See Acronym Geek, OPUS, http://www.acronymgeek.com/OPUS (optional description here) (as of Feb. 15, 2012, 16:49). |
| AMA | OPUS. Acronym Geek. February 15, 2012, 16:49. Available at: http://www.acronymgeek.com/OPUS. Accessed February 15, 2012, 16:49. |