Commentaries

Hebrews: A Commentary on the Epistles to the Hebrews (Hermenia) by Harold Attridge
The Epistle to the Hebrews (NICNT)
By F.F. Bruce
The Letter to the Hebrews in Social-Scientific Perspective By David deSilva
Perseverance in Gratitude: A Socio-Rhetorical Commentary on the Epistle to the Hebrews By David deSilva
Hebrews (NIV Application Commentary) By Guthrie
Hebrews (Interpretation Commentary) By Thomas Long
Letters and Homilies for Jewish Christians (Hebrews, James and Jude) By Ben Witherington
Hebrews for Everyone By Tom Wright

General

Dictionary of the Later New Testament and Its Developments By Ralph Martin