| APA | HAAO. (2012, February 16). In Acronym Geek. Retrieved 09:23, February 16, 2012, from http://www.acronymgeek.com/HAAO |
| MLA | "HAAO." Acronym Geek. (2012). Acronym Geek. 16 Feb 2012 <http://www.acronymgeek.com/HAAO>. |
| MHRA | 'HAAO', Acronym Geek, 16 February 2012, <http://www.acronymgeek.com/HAAO> [accessed 16 February 2012] |
| Chicago | "HAAO", http://www.acronymgeek.com/HAAO (accessed February 16, 2012). |
| CBE/CSE | HAAO [Internet]. Acronym Geek; 2012 Feb 16 [cited 2012 Feb 16]. Available from: http://www.acronymgeek.com/HAAO. |
| Bluebook | HAAO, http://www.acronymgeek.com/HAAO (last visited February 16, 2012). |
| Bluebook: Harvard JOLT | See Acronym Geek, HAAO, http://www.acronymgeek.com/HAAO (optional description here) (as of Feb. 16, 2012, 09:23). |
| AMA | HAAO. Acronym Geek. February 16, 2012, 09:23. Available at: http://www.acronymgeek.com/HAAO. Accessed February 16, 2012, 09:23. |