| APA | 4S. (2012, February 11). In Acronym Geek. Retrieved 21:53, February 11, 2012, from http://www.acronymgeek.com/4S |
| MLA | "4S." Acronym Geek. (2012). Acronym Geek. 11 Feb 2012 <http://www.acronymgeek.com/4S>. |
| MHRA | '4S', Acronym Geek, 11 February 2012, <http://www.acronymgeek.com/4S> [accessed 11 February 2012] |
| Chicago | "4S", http://www.acronymgeek.com/4S (accessed February 11, 2012). |
| CBE/CSE | 4S [Internet]. Acronym Geek; 2012 Feb 11 [cited 2012 Feb 11]. Available from: http://www.acronymgeek.com/4S. |
| Bluebook | 4S, http://www.acronymgeek.com/4S (last visited February 11, 2012). |
| Bluebook: Harvard JOLT | See Acronym Geek, 4S, http://www.acronymgeek.com/4S (optional description here) (as of Feb. 11, 2012, 21:53). |
| AMA | 4S. Acronym Geek. February 11, 2012, 21:53. Available at: http://www.acronymgeek.com/4S. Accessed February 11, 2012, 21:53. |