| APA | GREN. (2012, February 16). In Acronym Geek. Retrieved 11:27, February 16, 2012, from http://www.acronymgeek.com/GREN |
| MLA | "GREN." Acronym Geek. (2012). Acronym Geek. 16 Feb 2012 <http://www.acronymgeek.com/GREN>. |
| MHRA | 'GREN', Acronym Geek, 16 February 2012, <http://www.acronymgeek.com/GREN> [accessed 16 February 2012] |
| Chicago | "GREN", http://www.acronymgeek.com/GREN (accessed February 16, 2012). |
| CBE/CSE | GREN [Internet]. Acronym Geek; 2012 Feb 16 [cited 2012 Feb 16]. Available from: http://www.acronymgeek.com/GREN. |
| Bluebook | GREN, http://www.acronymgeek.com/GREN (last visited February 16, 2012). |
| Bluebook: Harvard JOLT | See Acronym Geek, GREN, http://www.acronymgeek.com/GREN (optional description here) (as of Feb. 16, 2012, 11:27). |
| AMA | GREN. Acronym Geek. February 16, 2012, 11:27. Available at: http://www.acronymgeek.com/GREN. Accessed February 16, 2012, 11:27. |