The Knights of Columbus Vatican Film Library, housed in Pius XII Library, is one of the premier centers for manuscript research in the U.S. The library has both a large collection of manuscripts on microfilm and a reference collection to support manuscript research. Detailed information is available by clicking on the link.
Georgetown University's The Labyrinth: Resources for Medieval Studies (archived and no longer maintained as of 2021) has a page for Manuscripts.
The sources listed below are only a small sampling of the electronic and print resources available either in the Vatican Film Library or Pius XII Library.
In Principio: Incipit Index of Latin Texts.
Please click "Enter Databases" button on the Brepols Web site, scroll to the appropriate icon and click on it to begin searching. In Principio is a index of approximately 1,000,000 incipits (first few words of text) of Medieval and Renaissance Latin manuscripts.
Electronic version of Paul Kristeller's multivolume listing of "uncatalogued or incompletely catalogued humanistic manuscripts of the Renaissance in Italian and other libraries" (to borrow from the subtitle of the printed work). Both the printed volumes (Z 6611 .H8 K7) and the CD-ROM version (Z6611.H8 K7 1995) of the database may also be consulted in the Vatican Film Library Reference collection.
Kristeller, Paul Oskar. Latin Manuscript Books Before 1600: A List of the Printed Catalogues and Unpublished Inventories of Extant Collections. 4th ed. revised and enlarged by Sigrid Kraemer. Muenchen: Monumenta Germaniae Historica, 1993.
Pius Spec Coll VFL Ref. DD3 .M84
Essentially a catalogue of manuscript catalogues. This tool will not identify manuscripts of individual writers but identifies catalogues where such information may be found. Four sections: "Bibliography and Statistics of Libraries and their Collections of Manuscripts," "Works Describing Manuscripts of More than One City," "Printed Catalogues and Handwritten Inventories of Individual Libraries, by Cities," and "Directories and Guides to Libraries and Archives."
Schönberger, Rolf and Brigitte Kible. Repertorium edierter Texte des Mittelalters aus dem Bereich der Philosophie und angrenzender Gebiete. Berlin: Akademie Verlag, 1994.
Pius Ref. B721.S33 1994
A bibliography, listing in alphabetical order by the Latinized form of a medieval author's name, the primary critical editions of medieval authors from Alcuin to Nicholas of Cua (800-1450). The "Philosophie" of the title is interpreted broadly and includes most if not all titles of theological relevance; the only types of texts that are deliberately excluded are texts of primarily literary or scientific (astronomy, medicine) character. Includes translations and dual-language editions.