| APA | OYPI. (2012, February 15). In Acronym Geek. Retrieved 22:21, February 15, 2012, from http://www.acronymgeek.com/OYPI |
| MLA | "OYPI." Acronym Geek. (2012). Acronym Geek. 15 Feb 2012 <http://www.acronymgeek.com/OYPI>. |
| MHRA | 'OYPI', Acronym Geek, 15 February 2012, <http://www.acronymgeek.com/OYPI> [accessed 15 February 2012] |
| Chicago | "OYPI", http://www.acronymgeek.com/OYPI (accessed February 15, 2012). |
| CBE/CSE | OYPI [Internet]. Acronym Geek; 2012 Feb 15 [cited 2012 Feb 15]. Available from: http://www.acronymgeek.com/OYPI. |
| Bluebook | OYPI, http://www.acronymgeek.com/OYPI (last visited February 15, 2012). |
| Bluebook: Harvard JOLT | See Acronym Geek, OYPI, http://www.acronymgeek.com/OYPI (optional description here) (as of Feb. 15, 2012, 22:21). |
| AMA | OYPI. Acronym Geek. February 15, 2012, 22:21. Available at: http://www.acronymgeek.com/OYPI. Accessed February 15, 2012, 22:21. |