| APA | HHDN. (2012, February 15). In Acronym Geek. Retrieved 17:17, February 15, 2012, from http://www.acronymgeek.com/HHDN |
| MLA | "HHDN." Acronym Geek. (2012). Acronym Geek. 15 Feb 2012 <http://www.acronymgeek.com/HHDN>. |
| MHRA | 'HHDN', Acronym Geek, 15 February 2012, <http://www.acronymgeek.com/HHDN> [accessed 15 February 2012] |
| Chicago | "HHDN", http://www.acronymgeek.com/HHDN (accessed February 15, 2012). |
| CBE/CSE | HHDN [Internet]. Acronym Geek; 2012 Feb 15 [cited 2012 Feb 15]. Available from: http://www.acronymgeek.com/HHDN. |
| Bluebook | HHDN, http://www.acronymgeek.com/HHDN (last visited February 15, 2012). |
| Bluebook: Harvard JOLT | See Acronym Geek, HHDN, http://www.acronymgeek.com/HHDN (optional description here) (as of Feb. 15, 2012, 17:17). |
| AMA | HHDN. Acronym Geek. February 15, 2012, 17:17. Available at: http://www.acronymgeek.com/HHDN. Accessed February 15, 2012, 17:17. |