| APA | G4S. (2012, February 14). In Acronym Geek. Retrieved 09:46, February 14, 2012, from http://www.acronymgeek.com/G4S |
| MLA | "G4S." Acronym Geek. (2012). Acronym Geek. 14 Feb 2012 <http://www.acronymgeek.com/G4S>. |
| MHRA | 'G4S', Acronym Geek, 14 February 2012, <http://www.acronymgeek.com/G4S> [accessed 14 February 2012] |
| Chicago | "G4S", http://www.acronymgeek.com/G4S (accessed February 14, 2012). |
| CBE/CSE | G4S [Internet]. Acronym Geek; 2012 Feb 14 [cited 2012 Feb 14]. Available from: http://www.acronymgeek.com/G4S. |
| Bluebook | G4S, http://www.acronymgeek.com/G4S (last visited February 14, 2012). |
| Bluebook: Harvard JOLT | See Acronym Geek, G4S, http://www.acronymgeek.com/G4S (optional description here) (as of Feb. 14, 2012, 09:46). |
| AMA | G4S. Acronym Geek. February 14, 2012, 09:46. Available at: http://www.acronymgeek.com/G4S. Accessed February 14, 2012, 09:46. |