| APA | FOS. (2012, February 13). In Acronym Geek. Retrieved 21:05, February 13, 2012, from http://www.acronymgeek.com/FOS |
| MLA | "FOS." Acronym Geek. (2012). Acronym Geek. 13 Feb 2012 <http://www.acronymgeek.com/FOS>. |
| MHRA | 'FOS', Acronym Geek, 13 February 2012, <http://www.acronymgeek.com/FOS> [accessed 13 February 2012] |
| Chicago | "FOS", http://www.acronymgeek.com/FOS (accessed February 13, 2012). |
| CBE/CSE | FOS [Internet]. Acronym Geek; 2012 Feb 13 [cited 2012 Feb 13]. Available from: http://www.acronymgeek.com/FOS. |
| Bluebook | FOS, http://www.acronymgeek.com/FOS (last visited February 13, 2012). |
| Bluebook: Harvard JOLT | See Acronym Geek, FOS, http://www.acronymgeek.com/FOS (optional description here) (as of Feb. 13, 2012, 21:05). |
| AMA | FOS. Acronym Geek. February 13, 2012, 21:05. Available at: http://www.acronymgeek.com/FOS. Accessed February 13, 2012, 21:05. |