| APA | HEAO. (2012, February 10). In Acronym Geek. Retrieved 18:15, February 10, 2012, from http://www.acronymgeek.com/HEAO |
| MLA | "HEAO." Acronym Geek. (2012). Acronym Geek. 10 Feb 2012 <http://www.acronymgeek.com/HEAO>. |
| MHRA | 'HEAO', Acronym Geek, 10 February 2012, <http://www.acronymgeek.com/HEAO> [accessed 10 February 2012] |
| Chicago | "HEAO", http://www.acronymgeek.com/HEAO (accessed February 10, 2012). |
| CBE/CSE | HEAO [Internet]. Acronym Geek; 2012 Feb 10 [cited 2012 Feb 10]. Available from: http://www.acronymgeek.com/HEAO. |
| Bluebook | HEAO, http://www.acronymgeek.com/HEAO (last visited February 10, 2012). |
| Bluebook: Harvard JOLT | See Acronym Geek, HEAO, http://www.acronymgeek.com/HEAO (optional description here) (as of Feb. 10, 2012, 18:15). |
| AMA | HEAO. Acronym Geek. February 10, 2012, 18:15. Available at: http://www.acronymgeek.com/HEAO. Accessed February 10, 2012, 18:15. |