| APA | PHD. (2012, February 9). In Acronym Geek. Retrieved 13:03, February 9, 2012, from http://www.acronymgeek.com/PHD |
| MLA | "PHD." Acronym Geek. (2012). Acronym Geek. 9 Feb 2012 <http://www.acronymgeek.com/PHD>. |
| MHRA | 'PHD', Acronym Geek, 9 February 2012, <http://www.acronymgeek.com/PHD> [accessed 9 February 2012] |
| Chicago | "PHD", http://www.acronymgeek.com/PHD (accessed February 9, 2012). |
| CBE/CSE | PHD [Internet]. Acronym Geek; 2012 Feb 9 [cited 2012 Feb 9]. Available from: http://www.acronymgeek.com/PHD. |
| Bluebook | PHD, http://www.acronymgeek.com/PHD (last visited February 9, 2012). |
| Bluebook: Harvard JOLT | See Acronym Geek, PHD, http://www.acronymgeek.com/PHD (optional description here) (as of Feb. 9, 2012, 13:03). |
| AMA | PHD. Acronym Geek. February 9, 2012, 13:03. Available at: http://www.acronymgeek.com/PHD. Accessed February 9, 2012, 13:03. |