| APA | PRPO. (2012, February 11). In Acronym Geek. Retrieved 21:08, February 11, 2012, from http://www.acronymgeek.com/PRPO |
| MLA | "PRPO." Acronym Geek. (2012). Acronym Geek. 11 Feb 2012 <http://www.acronymgeek.com/PRPO>. |
| MHRA | 'PRPO', Acronym Geek, 11 February 2012, <http://www.acronymgeek.com/PRPO> [accessed 11 February 2012] |
| Chicago | "PRPO", http://www.acronymgeek.com/PRPO (accessed February 11, 2012). |
| CBE/CSE | PRPO [Internet]. Acronym Geek; 2012 Feb 11 [cited 2012 Feb 11]. Available from: http://www.acronymgeek.com/PRPO. |
| Bluebook | PRPO, http://www.acronymgeek.com/PRPO (last visited February 11, 2012). |
| Bluebook: Harvard JOLT | See Acronym Geek, PRPO, http://www.acronymgeek.com/PRPO (optional description here) (as of Feb. 11, 2012, 21:08). |
| AMA | PRPO. Acronym Geek. February 11, 2012, 21:08. Available at: http://www.acronymgeek.com/PRPO. Accessed February 11, 2012, 21:08. |