Collver, Terra L. "Arthur Bibliography."

Lupack, Alan. "Post-Medieval Arthurian Literature in English (Other than Fiction): A Preliminary Bibliography."

Moore, Cindy Tittle. "Arthurian Booklist."

Nelson, Lynn. "Arthur's Britian," ORB: Online Reference Book for Medieval Studies.

Vermaat, Robert M., ed. "The Vortigern Studies Bibliography."

Note: This listing is not meant to be exhaustive or even representative of bibliographies available on the web. This listing includes only bibliographies that I find helpful, comprehensive and easy to use.