You should always be wary of your sources no matter what subject you are researching. And no subject requires as much caution as religion. You’d only have to be half-aware of world events over the last 2,000 years to realize that religion is a controversial subject. Relying on published sources is a good idea — knowing about the author and publisher at least gives you a reasonable expectation of the bias behind the information found. Because everything is biased. See if you can figure out what that bias is.
Search for “Islam” in Britannica.
Why start with anything else? Britannica has a reputation for reliable information.
Published articles about Islam. The GVRL is a database of encyclopedias and specialized reference sources – all published by well-known and reputable sources. Most importantly, these articles are written by historians and academic scholars.
Islam (World History in Context)
Published references articles
More in depth: Book-length sources
Full-length e-books and articles about Islam.