| APA | HPA. (2012, February 13). In Acronym Geek. Retrieved 21:43, February 13, 2012, from http://www.acronymgeek.com/HPA |
| MLA | "HPA." Acronym Geek. (2012). Acronym Geek. 13 Feb 2012 <http://www.acronymgeek.com/HPA>. |
| MHRA | 'HPA', Acronym Geek, 13 February 2012, <http://www.acronymgeek.com/HPA> [accessed 13 February 2012] |
| Chicago | "HPA", http://www.acronymgeek.com/HPA (accessed February 13, 2012). |
| CBE/CSE | HPA [Internet]. Acronym Geek; 2012 Feb 13 [cited 2012 Feb 13]. Available from: http://www.acronymgeek.com/HPA. |
| Bluebook | HPA, http://www.acronymgeek.com/HPA (last visited February 13, 2012). |
| Bluebook: Harvard JOLT | See Acronym Geek, HPA, http://www.acronymgeek.com/HPA (optional description here) (as of Feb. 13, 2012, 21:43). |
| AMA | HPA. Acronym Geek. February 13, 2012, 21:43. Available at: http://www.acronymgeek.com/HPA. Accessed February 13, 2012, 21:43. |