| APA | R4. (2012, February 14). In Acronym Geek. Retrieved 06:54, February 14, 2012, from http://www.acronymgeek.com/R4 |
| MLA | "R4." Acronym Geek. (2012). Acronym Geek. 14 Feb 2012 <http://www.acronymgeek.com/R4>. |
| MHRA | 'R4', Acronym Geek, 14 February 2012, <http://www.acronymgeek.com/R4> [accessed 14 February 2012] |
| Chicago | "R4", http://www.acronymgeek.com/R4 (accessed February 14, 2012). |
| CBE/CSE | R4 [Internet]. Acronym Geek; 2012 Feb 14 [cited 2012 Feb 14]. Available from: http://www.acronymgeek.com/R4. |
| Bluebook | R4, http://www.acronymgeek.com/R4 (last visited February 14, 2012). |
| Bluebook: Harvard JOLT | See Acronym Geek, R4, http://www.acronymgeek.com/R4 (optional description here) (as of Feb. 14, 2012, 06:54). |
| AMA | R4. Acronym Geek. February 14, 2012, 06:54. Available at: http://www.acronymgeek.com/R4. Accessed February 14, 2012, 06:54. |