| APA | SP4. (2012, February 14). In Acronym Geek. Retrieved 10:15, February 14, 2012, from http://www.acronymgeek.com/SP4 |
| MLA | "SP4." Acronym Geek. (2012). Acronym Geek. 14 Feb 2012 <http://www.acronymgeek.com/SP4>. |
| MHRA | 'SP4', Acronym Geek, 14 February 2012, <http://www.acronymgeek.com/SP4> [accessed 14 February 2012] |
| Chicago | "SP4", http://www.acronymgeek.com/SP4 (accessed February 14, 2012). |
| CBE/CSE | SP4 [Internet]. Acronym Geek; 2012 Feb 14 [cited 2012 Feb 14]. Available from: http://www.acronymgeek.com/SP4. |
| Bluebook | SP4, http://www.acronymgeek.com/SP4 (last visited February 14, 2012). |
| Bluebook: Harvard JOLT | See Acronym Geek, SP4, http://www.acronymgeek.com/SP4 (optional description here) (as of Feb. 14, 2012, 10:15). |
| AMA | SP4. Acronym Geek. February 14, 2012, 10:15. Available at: http://www.acronymgeek.com/SP4. Accessed February 14, 2012, 10:15. |