| APA | PENR. (2012, February 14). In Acronym Geek. Retrieved 20:08, February 14, 2012, from http://www.acronymgeek.com/PENR |
| MLA | "PENR." Acronym Geek. (2012). Acronym Geek. 14 Feb 2012 <http://www.acronymgeek.com/PENR>. |
| MHRA | 'PENR', Acronym Geek, 14 February 2012, <http://www.acronymgeek.com/PENR> [accessed 14 February 2012] |
| Chicago | "PENR", http://www.acronymgeek.com/PENR (accessed February 14, 2012). |
| CBE/CSE | PENR [Internet]. Acronym Geek; 2012 Feb 14 [cited 2012 Feb 14]. Available from: http://www.acronymgeek.com/PENR. |
| Bluebook | PENR, http://www.acronymgeek.com/PENR (last visited February 14, 2012). |
| Bluebook: Harvard JOLT | See Acronym Geek, PENR, http://www.acronymgeek.com/PENR (optional description here) (as of Feb. 14, 2012, 20:08). |
| AMA | PENR. Acronym Geek. February 14, 2012, 20:08. Available at: http://www.acronymgeek.com/PENR. Accessed February 14, 2012, 20:08. |