What makes a source primary?
Depends on the topic; it can be complicated.
Talk specifics with your advisor.
Very basic, simplistic definition: What is a primary source?
Browse footnotes and bibliographies of books, encyclopedias, and articles for information about primary sources.
Search the Library Catalog for primary sources--both unpublished manuscripts and modern editions in print and online, sometimes in translation, of original primary medieval sources. Use the guided keyword search with terms like:
sources
diaries
personal narrative
interview
letters
Selected sources in English Translation
Translated texts for Historians Classical and medieval primary sources in translation.
Manchester medieval sources. Translated texts on a wide variety of topics published in part or in full as print books and ebooks.
Loeb Classical Library A fully searchable, virtual library of Greek and Latin literature with English translations. Includes epic and lyric poetry; tragedy and comedy; history, travel, philosophy, and oratory; the great medical writers and mathematicians; and, those Church Fathers who made particular use of pagan culture.
CELT, the Corpus of Electronic Texts Online corpus of multilingual texts of Irish literature and history and the arts. Includes Old, Middle, Classical and Early Modern Irish, Scottish Gaelic, Latin, English and German, French, and English translations of Irish texts. It is Ireland's longest running Humanities Computing/Digital Humanities project.
British History Online Some of the core printed primary and secondary sources for the medieval and modern history of the British Isles. Created by the Institute of Historical Research and the History of Parliament Trust.
For a selection of the writings of the Church Fathers in English full-text online, see The Catholic Encyclopedia online's new Fathers section or Early Church Fathers
Internet Medieval Sourcebook (Paul Halsall, Editor) selected, excerpted primary sources full text online
A good place to get started; a good way to see what might be readily available. In most cases, these are not the best editions (which are copyrighted) so check the library catalog for more recent complete and critical translations (or email me for help). See also, Selected Medieval Sources: Islam and Jewish
Ferguson, Mary Anne. Bibliography of English translations from medieval sources, 1943-1967. New York, Columbia University Press, 1974. (Olin Library Graduate Study Center, Room 501 and Olin Reference Z6517 .F35) and Bibliography of English translations from medieval sources, by Clarissa P. Farrar and Austin P. Evans. New York, Columbia University Press, 1946. (Olin Library Graduate Study Center, Room 501 and Olin Reference Z6517 .F24). Outdated and superseded, but can still be useful on occasion, especially for brief works (a single letter or poem) or excerpts of longer works contained within books or articles.
Venti Belli A list of additional primary sources, some in English.