Last night I came across the web site of J. Paul Tanner who provides a variety of resources primarily on biblical studies. He has extensive notes on the book of Hebrews and also includes a 37 page bibliography which contains numerous articles that I have not come across before (and that is saying something). Unfortunately, I cannot link directly to the bibliography, but if you go to his page, look for the link "New Test Notes" and then for the link to "Hebrews" you will find numerous pdf files with his notes and bibliography.
Update: Here is the link to the bibliography. Thanks to Nick Norelli.