| APA | PSI. (2012, February 14). In Acronym Geek. Retrieved 07:13, February 14, 2012, from http://www.acronymgeek.com/PSI |
| MLA | "PSI." Acronym Geek. (2012). Acronym Geek. 14 Feb 2012 <http://www.acronymgeek.com/PSI>. |
| MHRA | 'PSI', Acronym Geek, 14 February 2012, <http://www.acronymgeek.com/PSI> [accessed 14 February 2012] |
| Chicago | "PSI", http://www.acronymgeek.com/PSI (accessed February 14, 2012). |
| CBE/CSE | PSI [Internet]. Acronym Geek; 2012 Feb 14 [cited 2012 Feb 14]. Available from: http://www.acronymgeek.com/PSI. |
| Bluebook | PSI, http://www.acronymgeek.com/PSI (last visited February 14, 2012). |
| Bluebook: Harvard JOLT | See Acronym Geek, PSI, http://www.acronymgeek.com/PSI (optional description here) (as of Feb. 14, 2012, 07:13). |
| AMA | PSI. Acronym Geek. February 14, 2012, 07:13. Available at: http://www.acronymgeek.com/PSI. Accessed February 14, 2012, 07:13. |