| APA | PEO. (2012, February 15). In Acronym Geek. Retrieved 03:15, February 15, 2012, from http://www.acronymgeek.com/PEO |
| MLA | "PEO." Acronym Geek. (2012). Acronym Geek. 15 Feb 2012 <http://www.acronymgeek.com/PEO>. |
| MHRA | 'PEO', Acronym Geek, 15 February 2012, <http://www.acronymgeek.com/PEO> [accessed 15 February 2012] |
| Chicago | "PEO", http://www.acronymgeek.com/PEO (accessed February 15, 2012). |
| CBE/CSE | PEO [Internet]. Acronym Geek; 2012 Feb 15 [cited 2012 Feb 15]. Available from: http://www.acronymgeek.com/PEO. |
| Bluebook | PEO, http://www.acronymgeek.com/PEO (last visited February 15, 2012). |
| Bluebook: Harvard JOLT | See Acronym Geek, PEO, http://www.acronymgeek.com/PEO (optional description here) (as of Feb. 15, 2012, 03:15). |
| AMA | PEO. Acronym Geek. February 15, 2012, 03:15. Available at: http://www.acronymgeek.com/PEO. Accessed February 15, 2012, 03:15. |