Isaiah 40â€“66: A Commentary by Shalom Paul from the Eerdmans Critical Commentary series, normally $50.
From the introduction:
If you don't already use Logos software, it's not too difficult to create a free account and in my opinion, it's worth it for this book alone.The Masoretic book of Isaiah is composed of two distinct sections written by two different authors at different times. The first section (chaps. 1â€“39, with the possible exceptions of chaps. 34 and 35; see below) was composed by Isaiah ben Amoz of Jerusalem (First or Proto-Isaiah), and the second by an anonymous prophet, referred to as Second or Deutero-Isaiah, whose prophecies (encompassing chaps. 40â€“66) were added to the opus of his predecessor.