We now have access to International Medieval Bibliography online. The IMB is one of the leading bibliographies of the European Middle Ages (c. 400-1500). The IMB now comprises 300,000 articles, all of which are fully classified by date, subject and location, and provide full bibliographical records. The discipline areas to which the IMB is relevant include Classics, English Language and Literature, History and Archaeology, Theology and Philosophy, Medieval European Languages and Literatures, Arabic and Islamic Studies, History of Education, Art History, Music, Theatre and Performance Arts, Rhetoric and Communication Studies.
When you click on the link above, it will take you to the Brepolis publisher's screen. Click where it says "enter databases":
Once you click on Enter Database, select International Medieval Bibliography under Medieval Bibliographies:
You can search by author, title, language, and year of publication. One really nice search feature is the thematic search option. You can search by discipline (there are options like canon law, hagiography, printing history, etc.) and by area (places like British Isles, Low Countries, South-Eastern Europe, etc.).
There's a limit of three simultaneous users at once, so be careful to not use it the night before your research is due (in case three other people have the same idea at the same time)!