| APA | PORTIS. (2012, February 11). In Acronym Geek. Retrieved 17:37, February 11, 2012, from http://www.acronymgeek.com/PORTIS |
| MLA | "PORTIS." Acronym Geek. (2012). Acronym Geek. 11 Feb 2012 <http://www.acronymgeek.com/PORTIS>. |
| MHRA | 'PORTIS', Acronym Geek, 11 February 2012, <http://www.acronymgeek.com/PORTIS> [accessed 11 February 2012] |
| Chicago | "PORTIS", http://www.acronymgeek.com/PORTIS (accessed February 11, 2012). |
| CBE/CSE | PORTIS [Internet]. Acronym Geek; 2012 Feb 11 [cited 2012 Feb 11]. Available from: http://www.acronymgeek.com/PORTIS. |
| Bluebook | PORTIS, http://www.acronymgeek.com/PORTIS (last visited February 11, 2012). |
| Bluebook: Harvard JOLT | See Acronym Geek, PORTIS, http://www.acronymgeek.com/PORTIS (optional description here) (as of Feb. 11, 2012, 17:37). |
| AMA | PORTIS. Acronym Geek. February 11, 2012, 17:37. Available at: http://www.acronymgeek.com/PORTIS. Accessed February 11, 2012, 17:37. |