| APA | PTD. (2012, February 9). In Acronym Geek. Retrieved 19:37, February 9, 2012, from http://www.acronymgeek.com/PTD |
| MLA | "PTD." Acronym Geek. (2012). Acronym Geek. 9 Feb 2012 <http://www.acronymgeek.com/PTD>. |
| MHRA | 'PTD', Acronym Geek, 9 February 2012, <http://www.acronymgeek.com/PTD> [accessed 9 February 2012] |
| Chicago | "PTD", http://www.acronymgeek.com/PTD (accessed February 9, 2012). |
| CBE/CSE | PTD [Internet]. Acronym Geek; 2012 Feb 9 [cited 2012 Feb 9]. Available from: http://www.acronymgeek.com/PTD. |
| Bluebook | PTD, http://www.acronymgeek.com/PTD (last visited February 9, 2012). |
| Bluebook: Harvard JOLT | See Acronym Geek, PTD, http://www.acronymgeek.com/PTD (optional description here) (as of Feb. 9, 2012, 19:37). |
| AMA | PTD. Acronym Geek. February 9, 2012, 19:37. Available at: http://www.acronymgeek.com/PTD. Accessed February 9, 2012, 19:37. |