Perma.cc was created by the Harvard Law Library. The Bluebook, the style guide for the legal citation system in the United States, suggests you include both the Perma Link and the original URL in the citation.
The 20th Edition of The Bluebook Rule 18.2.1(d) states:
“Archiving of Internet sources is encouraged, but only when a reliable archival tool is available. For citations to Internet sources, append the archive URL to the full citation in brackets” – the rule includes the following example:
Letter from Rose M. Oswald Poels, President/CEO, Wis. Bankers Ass’n, to Elizabeth M. Murphy, Sec’y, SEC (Sept. 17, 2013), http://www.sec.gov/comments/s7-03-13/s70313-178.pdf [http://perma.cc/B7Z7D9DJ].
Perma.cc is also the example used to demonstrate the archived sources rule in the Rule 18.1 Basic Citation Forms for Internet Sources table on page 179:
Rocio Gonzalez, Puerto Rico’s Status Debate Continues as Island Marks 61 Years as a Commonwealth, Huffington Post (July 25, 2013, 9:00 AM), http://www.huffingtonpost.com/2013/07/25/puerto-rico-status-debate_n_3651755.html [http://perma.cc/C6UP-96HN].
