| APA | NPEI. (2012, February 16). In Acronym Geek. Retrieved 10:29, February 16, 2012, from http://www.acronymgeek.com/NPEI |
| MLA | "NPEI." Acronym Geek. (2012). Acronym Geek. 16 Feb 2012 <http://www.acronymgeek.com/NPEI>. |
| MHRA | 'NPEI', Acronym Geek, 16 February 2012, <http://www.acronymgeek.com/NPEI> [accessed 16 February 2012] |
| Chicago | "NPEI", http://www.acronymgeek.com/NPEI (accessed February 16, 2012). |
| CBE/CSE | NPEI [Internet]. Acronym Geek; 2012 Feb 16 [cited 2012 Feb 16]. Available from: http://www.acronymgeek.com/NPEI. |
| Bluebook | NPEI, http://www.acronymgeek.com/NPEI (last visited February 16, 2012). |
| Bluebook: Harvard JOLT | See Acronym Geek, NPEI, http://www.acronymgeek.com/NPEI (optional description here) (as of Feb. 16, 2012, 10:29). |
| AMA | NPEI. Acronym Geek. February 16, 2012, 10:29. Available at: http://www.acronymgeek.com/NPEI. Accessed February 16, 2012, 10:29. |