| APA | SPEI. (2012, February 16). In Acronym Geek. Retrieved 23:26, February 16, 2012, from http://www.acronymgeek.com/SPEI |
| MLA | "SPEI." Acronym Geek. (2012). Acronym Geek. 16 Feb 2012 <http://www.acronymgeek.com/SPEI>. |
| MHRA | 'SPEI', Acronym Geek, 16 February 2012, <http://www.acronymgeek.com/SPEI> [accessed 16 February 2012] |
| Chicago | "SPEI", http://www.acronymgeek.com/SPEI (accessed February 16, 2012). |
| CBE/CSE | SPEI [Internet]. Acronym Geek; 2012 Feb 16 [cited 2012 Feb 16]. Available from: http://www.acronymgeek.com/SPEI. |
| Bluebook | SPEI, http://www.acronymgeek.com/SPEI (last visited February 16, 2012). |
| Bluebook: Harvard JOLT | See Acronym Geek, SPEI, http://www.acronymgeek.com/SPEI (optional description here) (as of Feb. 16, 2012, 23:26). |
| AMA | SPEI. Acronym Geek. February 16, 2012, 23:26. Available at: http://www.acronymgeek.com/SPEI. Accessed February 16, 2012, 23:26. |