Q. How do I find commentaries on Isaiah?

The best way is to use the Advanced search mode in MARTIN, the library catalog.  Enter search terms isaiah and commentaries.  On the next drop down menu, select "all of these" so that your search will look for both terms.  In the last drop down, choose Subject so that the search will be limited to terms in the subject heading field.

Once you have the list of results, note that most of the call numbers will look very much alike, e.g. BS1515.3.  This will be the area of the bookstacks where you should begin browsing for the Isaiah commentaries.  The same process will work for commentaries on other books of the Bible.