| APA | HDU. (2012, February 10). In Acronym Geek. Retrieved 17:18, February 10, 2012, from http://www.acronymgeek.com/HDU |
| MLA | "HDU." Acronym Geek. (2012). Acronym Geek. 10 Feb 2012 <http://www.acronymgeek.com/HDU>. |
| MHRA | 'HDU', Acronym Geek, 10 February 2012, <http://www.acronymgeek.com/HDU> [accessed 10 February 2012] |
| Chicago | "HDU", http://www.acronymgeek.com/HDU (accessed February 10, 2012). |
| CBE/CSE | HDU [Internet]. Acronym Geek; 2012 Feb 10 [cited 2012 Feb 10]. Available from: http://www.acronymgeek.com/HDU. |
| Bluebook | HDU, http://www.acronymgeek.com/HDU (last visited February 10, 2012). |
| Bluebook: Harvard JOLT | See Acronym Geek, HDU, http://www.acronymgeek.com/HDU (optional description here) (as of Feb. 10, 2012, 17:18). |
| AMA | HDU. Acronym Geek. February 10, 2012, 17:18. Available at: http://www.acronymgeek.com/HDU. Accessed February 10, 2012, 17:18. |