A classic Greek lexicon useful for every theology student. Note that Thayer was a universalist, so be careful with any word dealing with salvation, and also the Trinity (his definition of "Christ" would seem to doubt Jesus' deity). Basically the majority of his word definitions are from standard usage in the Greek NT and classical literature, so in theologically charged words, be careful.

Thompson Chain Reference Bible Dictionary is a Bible Cross Reference work.

The original Torrey's Topical Textbookd had on 628 entries and 20,000 Scripture Cross-References, the New Topical Textbook was published with 20,000 Topics and Sub-topics and 30,000 Bible References.

Treasury of Scripture Knowledge is essentially a cross reference work, set up similar to a commentary (in a commentary format for theWord), and under each verse of the Bible, there are cross references (which theWord makes it very easy to mouse over the references and read them without having to click anything).