I want to thank Scott Hahn for alerting to me to his online articles on Hebrews. The following two articles have been added:
Hahn, Scott. "A Broken Covenant and the Curse of Death: A Study of Hebrews 9:15-22." Catholic Biblical Quarterly 66.3 (2004): 416-36.
Hahn, Scott. "Covenant, Cult, and the Curse-of-Death: Διαθηκη in Heb 9:15-22." Pages 65-88 in Hebrews: Contemporary Methods - New Insights. Edited by Gabriella Gelardini. Leiden: Brill, 2005.
He also informed me of his recent volume in the Anchor Yale Bible Reference Library containing a lengthy chapter on Hebrews:
Chapter 10: "Hebrews 1-9: Covenant, Oath, and Royal Priestly Primogeniture." Pages 278-331, 467-482 in Kinship by Covenant: A Canonical Approach to the Fulfillment of God's Saving Promises. Yale, 2009.
As a bonus, you can click on his name above to access all of his online articles and his personal website. :-)