| APA | HHFO. (2012, February 17). In Acronym Geek. Retrieved 07:36, February 17, 2012, from http://www.acronymgeek.com/HHFO |
| MLA | "HHFO." Acronym Geek. (2012). Acronym Geek. 17 Feb 2012 <http://www.acronymgeek.com/HHFO>. |
| MHRA | 'HHFO', Acronym Geek, 17 February 2012, <http://www.acronymgeek.com/HHFO> [accessed 17 February 2012] |
| Chicago | "HHFO", http://www.acronymgeek.com/HHFO (accessed February 17, 2012). |
| CBE/CSE | HHFO [Internet]. Acronym Geek; 2012 Feb 17 [cited 2012 Feb 17]. Available from: http://www.acronymgeek.com/HHFO. |
| Bluebook | HHFO, http://www.acronymgeek.com/HHFO (last visited February 17, 2012). |
| Bluebook: Harvard JOLT | See Acronym Geek, HHFO, http://www.acronymgeek.com/HHFO (optional description here) (as of Feb. 17, 2012, 07:36). |
| AMA | HHFO. Acronym Geek. February 17, 2012, 07:36. Available at: http://www.acronymgeek.com/HHFO. Accessed February 17, 2012, 07:36. |