| APA | P4Y. (2012, February 14). In Acronym Geek. Retrieved 19:41, February 14, 2012, from http://www.acronymgeek.com/P4Y |
| MLA | "P4Y." Acronym Geek. (2012). Acronym Geek. 14 Feb 2012 <http://www.acronymgeek.com/P4Y>. |
| MHRA | 'P4Y', Acronym Geek, 14 February 2012, <http://www.acronymgeek.com/P4Y> [accessed 14 February 2012] |
| Chicago | "P4Y", http://www.acronymgeek.com/P4Y (accessed February 14, 2012). |
| CBE/CSE | P4Y [Internet]. Acronym Geek; 2012 Feb 14 [cited 2012 Feb 14]. Available from: http://www.acronymgeek.com/P4Y. |
| Bluebook | P4Y, http://www.acronymgeek.com/P4Y (last visited February 14, 2012). |
| Bluebook: Harvard JOLT | See Acronym Geek, P4Y, http://www.acronymgeek.com/P4Y (optional description here) (as of Feb. 14, 2012, 19:41). |
| AMA | P4Y. Acronym Geek. February 14, 2012, 19:41. Available at: http://www.acronymgeek.com/P4Y. Accessed February 14, 2012, 19:41. |