| APA | HKOE. (2012, February 15). In Acronym Geek. Retrieved 04:51, February 15, 2012, from http://www.acronymgeek.com/HKOE |
| MLA | "HKOE." Acronym Geek. (2012). Acronym Geek. 15 Feb 2012 <http://www.acronymgeek.com/HKOE>. |
| MHRA | 'HKOE', Acronym Geek, 15 February 2012, <http://www.acronymgeek.com/HKOE> [accessed 15 February 2012] |
| Chicago | "HKOE", http://www.acronymgeek.com/HKOE (accessed February 15, 2012). |
| CBE/CSE | HKOE [Internet]. Acronym Geek; 2012 Feb 15 [cited 2012 Feb 15]. Available from: http://www.acronymgeek.com/HKOE. |
| Bluebook | HKOE, http://www.acronymgeek.com/HKOE (last visited February 15, 2012). |
| Bluebook: Harvard JOLT | See Acronym Geek, HKOE, http://www.acronymgeek.com/HKOE (optional description here) (as of Feb. 15, 2012, 04:51). |
| AMA | HKOE. Acronym Geek. February 15, 2012, 04:51. Available at: http://www.acronymgeek.com/HKOE. Accessed February 15, 2012, 04:51. |