| APA | HBPO. (2012, February 15). In Acronym Geek. Retrieved 19:26, February 15, 2012, from http://www.acronymgeek.com/HBPO |
| MLA | "HBPO." Acronym Geek. (2012). Acronym Geek. 15 Feb 2012 <http://www.acronymgeek.com/HBPO>. |
| MHRA | 'HBPO', Acronym Geek, 15 February 2012, <http://www.acronymgeek.com/HBPO> [accessed 15 February 2012] |
| Chicago | "HBPO", http://www.acronymgeek.com/HBPO (accessed February 15, 2012). |
| CBE/CSE | HBPO [Internet]. Acronym Geek; 2012 Feb 15 [cited 2012 Feb 15]. Available from: http://www.acronymgeek.com/HBPO. |
| Bluebook | HBPO, http://www.acronymgeek.com/HBPO (last visited February 15, 2012). |
| Bluebook: Harvard JOLT | See Acronym Geek, HBPO, http://www.acronymgeek.com/HBPO (optional description here) (as of Feb. 15, 2012, 19:26). |
| AMA | HBPO. Acronym Geek. February 15, 2012, 19:26. Available at: http://www.acronymgeek.com/HBPO. Accessed February 15, 2012, 19:26. |