| APA | HHD. (2012, February 13). In Acronym Geek. Retrieved 21:25, February 13, 2012, from http://www.acronymgeek.com/HHD |
| MLA | "HHD." Acronym Geek. (2012). Acronym Geek. 13 Feb 2012 <http://www.acronymgeek.com/HHD>. |
| MHRA | 'HHD', Acronym Geek, 13 February 2012, <http://www.acronymgeek.com/HHD> [accessed 13 February 2012] |
| Chicago | "HHD", http://www.acronymgeek.com/HHD (accessed February 13, 2012). |
| CBE/CSE | HHD [Internet]. Acronym Geek; 2012 Feb 13 [cited 2012 Feb 13]. Available from: http://www.acronymgeek.com/HHD. |
| Bluebook | HHD, http://www.acronymgeek.com/HHD (last visited February 13, 2012). |
| Bluebook: Harvard JOLT | See Acronym Geek, HHD, http://www.acronymgeek.com/HHD (optional description here) (as of Feb. 13, 2012, 21:25). |
| AMA | HHD. Acronym Geek. February 13, 2012, 21:25. Available at: http://www.acronymgeek.com/HHD. Accessed February 13, 2012, 21:25. |