Project Gutenberg, first begun in the 1970s, aims to provide free access to reading materials via the internet. The project currently includes over 50,000 open-access works, covering multiple subjects and representative of many time periods. Some of the works will be of interest to medievalists; editions of the Divine Comedy can be found in Italian on the site, for example, and other works of potential interest, both primary and secondary, are certainly to be found within the large collection. However, both the search and browse functions are outdated given current search engines. Even given the large number of volumes included, medieval works are more sparse than one might desire for inclusion in the MDR.
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Thesaurus Musicarum Latinarum
The Thesaurus Musicarum Latinarum is a database of digitized medieval Latin texts on the topic of music, broadly imagined. Housed at the University of Indiana, the project transcribes and digitizes texts on all topics related to medieval music from the 5th to 17th centuries and provides a database to house them. A user may search by title, author, topic, century, and numerous other qualities. Each text entry offers a brief synopsis and bibliography, including manuscripts in which the text appears.
The TML clearly outlines their transcription policies and provides all their material for free via a Creative Commons license.