| APA | S4I. (2012, February 14). In Acronym Geek. Retrieved 01:20, February 14, 2012, from http://www.acronymgeek.com/S4I |
| MLA | "S4I." Acronym Geek. (2012). Acronym Geek. 14 Feb 2012 <http://www.acronymgeek.com/S4I>. |
| MHRA | 'S4I', Acronym Geek, 14 February 2012, <http://www.acronymgeek.com/S4I> [accessed 14 February 2012] |
| Chicago | "S4I", http://www.acronymgeek.com/S4I (accessed February 14, 2012). |
| CBE/CSE | S4I [Internet]. Acronym Geek; 2012 Feb 14 [cited 2012 Feb 14]. Available from: http://www.acronymgeek.com/S4I. |
| Bluebook | S4I, http://www.acronymgeek.com/S4I (last visited February 14, 2012). |
| Bluebook: Harvard JOLT | See Acronym Geek, S4I, http://www.acronymgeek.com/S4I (optional description here) (as of Feb. 14, 2012, 01:20). |
| AMA | S4I. Acronym Geek. February 14, 2012, 01:20. Available at: http://www.acronymgeek.com/S4I. Accessed February 14, 2012, 01:20. |