OLD TESTAMENT COMMENTARIES:
Sets Covering More Than One Book of the Old Testament
*Keil, C.F. and F. Delitzsch. Biblical Commentary on the Old Testament (6 volumes; 1864, 1892). This commentary was recommended to me by a professor in Bible College over 30 years ago and I have never been disappointed. Still one of the best Old Testament commentary sets available (if not still the best) and you can download it for free.
NEW TESTAMENT COMMENTARIES
Sets Covering More Than One Book of the New Testament
**IVP New Testament Commentaries at BibleGateway
*Lightfoot, John. A Commentary on the New Testament From the Talmud and Hebraica.
*Lightfoot, Joseph Barber. (Commentaries and other works).
*Moule, Handley C.G. (Commentaries and other writings).
*Nicoll, W. Robertson (editor). The Expositor's Greek New Testament.
*Robertson, A.T. Word Pictures in the New Testament.
*International Critical Commentaries (Old and New Testment)
*Wilmhurst, Steve. A Ransom for Many: The Gospel of Mark Simply Explained. See "how the Gospel of Mark is connected to the Old Testament prophets."
*Haldane, Robert. Exposition on the Epistle to the Romans.
*Hodge, Charles. A Commentary on the Epistle to the Romans.
*Luther, Martin. Commentary on the Epistle to the Galatians. Also available for FREE in audiobook.
A lot more FREE commentaries available at the links below....
*StudyLight.org: 107 commentaries are hosted here! "StudyLight has more Bible commentaries, encyclopedias, dictionaries, lexicons and original language tools than any other website on the internet!"
*Ray Stedman commentaries at Blue Letter Bible
*Tyndale House hosts a very long list of the best commentaries available for free online.
*A humongous list of free commentaries at Bible Researcher (Old and New Testament)
*Tons of free New Testament Commentaries in Tyndale Seminary's "New Testament Reading Room"
*Tons of free Old Testament Commentaries in Tyndale Seminary's "Old Testament Reading Room"
*More than 90 commentaries available online. (Old and New Testmaent)
*More free commentaries. (Old and New Testament)
*Extensive list of Online Biblical Studies Resources.
*Exegetical Fallacies: Common Mistakes Every Student of the Bible Must Avoid by William D. Barrick (a free 11 page ebook)