| APA | SPEN. (2012, February 15). In Acronym Geek. Retrieved 23:33, February 15, 2012, from http://www.acronymgeek.com/SPEN |
| MLA | "SPEN." Acronym Geek. (2012). Acronym Geek. 15 Feb 2012 <http://www.acronymgeek.com/SPEN>. |
| MHRA | 'SPEN', Acronym Geek, 15 February 2012, <http://www.acronymgeek.com/SPEN> [accessed 15 February 2012] |
| Chicago | "SPEN", http://www.acronymgeek.com/SPEN (accessed February 15, 2012). |
| CBE/CSE | SPEN [Internet]. Acronym Geek; 2012 Feb 15 [cited 2012 Feb 15]. Available from: http://www.acronymgeek.com/SPEN. |
| Bluebook | SPEN, http://www.acronymgeek.com/SPEN (last visited February 15, 2012). |
| Bluebook: Harvard JOLT | See Acronym Geek, SPEN, http://www.acronymgeek.com/SPEN (optional description here) (as of Feb. 15, 2012, 23:33). |
| AMA | SPEN. Acronym Geek. February 15, 2012, 23:33. Available at: http://www.acronymgeek.com/SPEN. Accessed February 15, 2012, 23:33. |