Atlases and maps are used to locate places and can also provide the history and significance of a site.
Bible dictionaries provide definitions and explanations to significant terms and subjects in the Holy Scriptures.
Commentaries are essays to assist in the understanding of passages in sacred books, texts, etc.
A concordance is an index to a book. It is arranged in alphabetical order and shows the location of each word in the book. Each concordance corresponds with a version of the Bible.