| APA | PPO. (2012, February 7). In Acronym Geek. Retrieved 22:56, February 7, 2012, from http://www.acronymgeek.com/PPO |
| MLA | "PPO." Acronym Geek. (2012). Acronym Geek. 7 Feb 2012 <http://www.acronymgeek.com/PPO>. |
| MHRA | 'PPO', Acronym Geek, 7 February 2012, <http://www.acronymgeek.com/PPO> [accessed 7 February 2012] |
| Chicago | "PPO", http://www.acronymgeek.com/PPO (accessed February 7, 2012). |
| CBE/CSE | PPO [Internet]. Acronym Geek; 2012 Feb 7 [cited 2012 Feb 7]. Available from: http://www.acronymgeek.com/PPO. |
| Bluebook | PPO, http://www.acronymgeek.com/PPO (last visited February 7, 2012). |
| Bluebook: Harvard JOLT | See Acronym Geek, PPO, http://www.acronymgeek.com/PPO (optional description here) (as of Feb. 7, 2012, 22:56). |
| AMA | PPO. Acronym Geek. February 7, 2012, 22:56. Available at: http://www.acronymgeek.com/PPO. Accessed February 7, 2012, 22:56. |