| APA | HDEF. (2012, February 15). In Acronym Geek. Retrieved 06:40, February 15, 2012, from http://www.acronymgeek.com/HDEF |
| MLA | "HDEF." Acronym Geek. (2012). Acronym Geek. 15 Feb 2012 <http://www.acronymgeek.com/HDEF>. |
| MHRA | 'HDEF', Acronym Geek, 15 February 2012, <http://www.acronymgeek.com/HDEF> [accessed 15 February 2012] |
| Chicago | "HDEF", http://www.acronymgeek.com/HDEF (accessed February 15, 2012). |
| CBE/CSE | HDEF [Internet]. Acronym Geek; 2012 Feb 15 [cited 2012 Feb 15]. Available from: http://www.acronymgeek.com/HDEF. |
| Bluebook | HDEF, http://www.acronymgeek.com/HDEF (last visited February 15, 2012). |
| Bluebook: Harvard JOLT | See Acronym Geek, HDEF, http://www.acronymgeek.com/HDEF (optional description here) (as of Feb. 15, 2012, 06:40). |
| AMA | HDEF. Acronym Geek. February 15, 2012, 06:40. Available at: http://www.acronymgeek.com/HDEF. Accessed February 15, 2012, 06:40. |