I have added links to a few resources that I have recently come across:
Dyer, Bryan R. “The Epistle to the Hebrews inRecent Research: Studies on the Author’s Identity, His Use of the OldTestament, and Theology.” Journal of Greco-Roman Christianity and Judaism 9 (2013): 104–31.
McNeile, Alan Hugh. “A Note on Heb. IX 12.” Journal
of Theological Studies 24.96 (July 1923): 402.
Redmond, Alan. "The Obsolete Covenant in Hebrews Chapter Eight." M.A. thesis, Providence Seminary, 2008.