| APA | HKOA. (2012, February 17). In Acronym Geek. Retrieved 02:55, February 17, 2012, from http://www.acronymgeek.com/HKOA |
| MLA | "HKOA." Acronym Geek. (2012). Acronym Geek. 17 Feb 2012 <http://www.acronymgeek.com/HKOA>. |
| MHRA | 'HKOA', Acronym Geek, 17 February 2012, <http://www.acronymgeek.com/HKOA> [accessed 17 February 2012] |
| Chicago | "HKOA", http://www.acronymgeek.com/HKOA (accessed February 17, 2012). |
| CBE/CSE | HKOA [Internet]. Acronym Geek; 2012 Feb 17 [cited 2012 Feb 17]. Available from: http://www.acronymgeek.com/HKOA. |
| Bluebook | HKOA, http://www.acronymgeek.com/HKOA (last visited February 17, 2012). |
| Bluebook: Harvard JOLT | See Acronym Geek, HKOA, http://www.acronymgeek.com/HKOA (optional description here) (as of Feb. 17, 2012, 02:55). |
| AMA | HKOA. Acronym Geek. February 17, 2012, 02:55. Available at: http://www.acronymgeek.com/HKOA. Accessed February 17, 2012, 02:55. |