| APA | PNBO. (2012, February 17). In Acronym Geek. Retrieved 00:27, February 17, 2012, from http://www.acronymgeek.com/PNBO |
| MLA | "PNBO." Acronym Geek. (2012). Acronym Geek. 17 Feb 2012 <http://www.acronymgeek.com/PNBO>. |
| MHRA | 'PNBO', Acronym Geek, 17 February 2012, <http://www.acronymgeek.com/PNBO> [accessed 17 February 2012] |
| Chicago | "PNBO", http://www.acronymgeek.com/PNBO (accessed February 17, 2012). |
| CBE/CSE | PNBO [Internet]. Acronym Geek; 2012 Feb 17 [cited 2012 Feb 17]. Available from: http://www.acronymgeek.com/PNBO. |
| Bluebook | PNBO, http://www.acronymgeek.com/PNBO (last visited February 17, 2012). |
| Bluebook: Harvard JOLT | See Acronym Geek, PNBO, http://www.acronymgeek.com/PNBO (optional description here) (as of Feb. 17, 2012, 00:27). |
| AMA | PNBO. Acronym Geek. February 17, 2012, 00:27. Available at: http://www.acronymgeek.com/PNBO. Accessed February 17, 2012, 00:27. |