| APA | BTU. (2012, February 8). In Acronym Geek. Retrieved 10:49, February 8, 2012, from http://www.acronymgeek.com/BTU |
| MLA | "BTU." Acronym Geek. (2012). Acronym Geek. 8 Feb 2012 <http://www.acronymgeek.com/BTU>. |
| MHRA | 'BTU', Acronym Geek, 8 February 2012, <http://www.acronymgeek.com/BTU> [accessed 8 February 2012] |
| Chicago | "BTU", http://www.acronymgeek.com/BTU (accessed February 8, 2012). |
| CBE/CSE | BTU [Internet]. Acronym Geek; 2012 Feb 8 [cited 2012 Feb 8]. Available from: http://www.acronymgeek.com/BTU. |
| Bluebook | BTU, http://www.acronymgeek.com/BTU (last visited February 8, 2012). |
| Bluebook: Harvard JOLT | See Acronym Geek, BTU, http://www.acronymgeek.com/BTU (optional description here) (as of Feb. 8, 2012, 10:49). |
| AMA | BTU. Acronym Geek. February 8, 2012, 10:49. Available at: http://www.acronymgeek.com/BTU. Accessed February 8, 2012, 10:49. |