"Primary sources are original records created at the time historical events occurred or well after events in the form of memoirs and oral histories. Primary sources may include letters, manuscripts, diaries, journals, newspapers, speeches, interviews, memoirs, documents produced by government agencies such as Congress or the Office of the President, photographs, audio recordings, moving pictures or video recordings, research data, and objects or artifacts such as works of art or ancient roads, buildings, tools, and weapons. These sources serve as the raw material to interpret the past, and when they are used along with previous interpretations by historians, they provide the resources necessary for historical research."
(American Library Association, Reference and User Services, History Section)
Primary sources can be found in digital archives/collections, databases, books, museums, archives, and out in the open.
Chances are you already found some primary sources through the books and articles you've search for.
To supplement that, here are some online repositories that have digitized primary sources. Some are available through SCU Library, and some are open access out on the Internet.
You can use the library online catalog, OSCAR, to find published primary sources or books that include reproductions of primary documents.
Primary sources can be found in databases, books, museums, archives, out in the open, and freely available online.
Chances are you already found some primary sources through the books and articles you've search for.
Here are some specific digital archives that have digitized primary sources.
To find other options for quality primary source digital archives on the Internet, trying Googling something like islamic digital collections.