A helpful suggestion from History Today on broken hyperlinks.

Digital library researchers at Los Alamos National Laboratory found in a survey of three and a half million scholarly articles from scientific journals between 1997 and 2012 that one in five links provided in the footnotes suffered from 'reference rot'. Another survey, this time of law and policy publications, revealed that after six years nearly half of URLs cited had become inaccessible. Historians (perhaps unsurprisingly, given their profession) have been slower to place this most modern of problems at the top of their agenda. They are, however, not immune from its effect. An American study of two leading history journals found that in articles published seven years earlier, 38 percent of web citations were dead. Missing web pages can sometimes be relocated by academics through digital archives, the biggest of them being the Wayback Machine in San Francisco. A good many web pages, however, have not been archived and are permanently irretrievable.

A tool called Perma.cc was launched in beta phase in 2014. Developed by the Harvard Law School Library, it ‘allows users to create citation links that will never break’. If you want to secure the future of an Internet link in your footnotes, you create an archived version of the page you are referring to and anyone later clicking on your link will be taken through to the archived version. This ‘permalink’ does not repair Internet citations that have already decayed, but it does effectively fix the problem going forward. It has already been taken up by law reviews in America.

It would be cool if philosophy papers had links, instead of just referencing paper editions.