| APA | PDO. (2012, February 14). In Acronym Geek. Retrieved 10:14, February 14, 2012, from http://www.acronymgeek.com/PDO |
| MLA | "PDO." Acronym Geek. (2012). Acronym Geek. 14 Feb 2012 <http://www.acronymgeek.com/PDO>. |
| MHRA | 'PDO', Acronym Geek, 14 February 2012, <http://www.acronymgeek.com/PDO> [accessed 14 February 2012] |
| Chicago | "PDO", http://www.acronymgeek.com/PDO (accessed February 14, 2012). |
| CBE/CSE | PDO [Internet]. Acronym Geek; 2012 Feb 14 [cited 2012 Feb 14]. Available from: http://www.acronymgeek.com/PDO. |
| Bluebook | PDO, http://www.acronymgeek.com/PDO (last visited February 14, 2012). |
| Bluebook: Harvard JOLT | See Acronym Geek, PDO, http://www.acronymgeek.com/PDO (optional description here) (as of Feb. 14, 2012, 10:14). |
| AMA | PDO. Acronym Geek. February 14, 2012, 10:14. Available at: http://www.acronymgeek.com/PDO. Accessed February 14, 2012, 10:14. |