| APA | ER. (2012, February 9). In Acronym Geek. Retrieved 15:28, February 9, 2012, from http://www.acronymgeek.com/ER |
| MLA | "ER." Acronym Geek. (2012). Acronym Geek. 9 Feb 2012 <http://www.acronymgeek.com/ER>. |
| MHRA | 'ER', Acronym Geek, 9 February 2012, <http://www.acronymgeek.com/ER> [accessed 9 February 2012] |
| Chicago | "ER", http://www.acronymgeek.com/ER (accessed February 9, 2012). |
| CBE/CSE | ER [Internet]. Acronym Geek; 2012 Feb 9 [cited 2012 Feb 9]. Available from: http://www.acronymgeek.com/ER. |
| Bluebook | ER, http://www.acronymgeek.com/ER (last visited February 9, 2012). |
| Bluebook: Harvard JOLT | See Acronym Geek, ER, http://www.acronymgeek.com/ER (optional description here) (as of Feb. 9, 2012, 15:28). |
| AMA | ER. Acronym Geek. February 9, 2012, 15:28. Available at: http://www.acronymgeek.com/ER. Accessed February 9, 2012, 15:28. |