We are now in the 8th edition of the Modern Languages Association Handbook. As more and more research is done digitally, rules are changing to make it easier to cite any type of source. From the MLA website:
The eighth edition of the MLA Handbook introduces a new model for entries in the works-cited list, one that reflects recent changes in how works are published and consulted. Previously, a writer created an entry by following the MLA’s instructions for the source’s publication format (book, DVD, Web page, etc.). That approach has become impractical today, since publication formats are often combined (a song listened to online, for example, could have been taken from a record album released decades ago) or are undefinable.
In the new model, the work’s publication format is not considered. Instead of asking, “How do I cite a book [or DVD or Web page]?” the writer creates an entry by consulting the MLA’s list of core elements—facts common to most works—which are assembled in a specific order. The MLA core elements appear below: