Books on Isaiah fall into the categories of large commentaries, those looking at Isaiah along a particular topic line, and those looking at just one portion of Isaiah. In the category of large, multi-volume commentaries that cover the entire book and take the approach of a single original author, the following are recommended:
Smith, Gary V., Isaiah 1-39, Christian Standard Commentary, Holman, Nashville, Tennessee, 2021, ISBN 978-1-5359-9658-7.
The second CSC volume is not yet available, therefore, for Isaiah 40 – 66, please refer to:
Smith, Gary V., Isaiah 1-39 VOL 15A and 40-66 VOL 15B, An Exegetical and Theological Exposition of Holy Scripture, The New American Commentary, B & H Publishing Group, Nashville, Tennessee, 2007, ISBN 978-0-8054-0115-8.
Oswalt, John N., “The Book of Isaiah”, NICOT, William B. Eerdmans Publishing Company, Grand Rapids, Michigan, 1986, ISBN 978-0-8028-2529-2.
Motyer, Alec J., (1973) The Prophecy of Isaiah, An Introduction & Commentary, Intervarsity Press, Downers Grove, Illinois, ISBN 978-0-8308-1593-7.
Young, Edward J., The Book of Isaiah, William B. Eerdmans Publishing Company, Grand Rapids, Michigan, 1969, ISBN-13: 978-0-8028-9552-3.
Volumes by Oswalt, Motyer, and Young, are all highly recommended by the Best Commentaries website, by the Best Bible Commentaries website in 2021, by Tim Challies in 2014, and by Keith Mathison in 2008. However, the volumes by Gary V. Smith are most highly rated on this webpage because of their focus on structure, and superb clarity of writing. The appreciation of structure is consistent with the specific focus of this website.
The above commentaries help readers understand what was written. For help understanding what Isaiah was following as he wrote, which will help you read yourself, this website and Isaiah Revisited are suggested. Please refer to the Books By Author page.
There are many more commentaries out there. However, my financial director has not allowed me to buy them all! A scored listing of commentaries can be found on the website Best Commentaries.