| APA | 4YI. (2012, February 10). In Acronym Geek. Retrieved 09:41, February 10, 2012, from http://www.acronymgeek.com/4YI |
| MLA | "4YI." Acronym Geek. (2012). Acronym Geek. 10 Feb 2012 <http://www.acronymgeek.com/4YI>. |
| MHRA | '4YI', Acronym Geek, 10 February 2012, <http://www.acronymgeek.com/4YI> [accessed 10 February 2012] |
| Chicago | "4YI", http://www.acronymgeek.com/4YI (accessed February 10, 2012). |
| CBE/CSE | 4YI [Internet]. Acronym Geek; 2012 Feb 10 [cited 2012 Feb 10]. Available from: http://www.acronymgeek.com/4YI. |
| Bluebook | 4YI, http://www.acronymgeek.com/4YI (last visited February 10, 2012). |
| Bluebook: Harvard JOLT | See Acronym Geek, 4YI, http://www.acronymgeek.com/4YI (optional description here) (as of Feb. 10, 2012, 09:41). |
| AMA | 4YI. Acronym Geek. February 10, 2012, 09:41. Available at: http://www.acronymgeek.com/4YI. Accessed February 10, 2012, 09:41. |