If you buy a second book for
studying the Bible, buy a Bible Dictionary or Encyclopedia:

What's the difference between a Bible Dictionary and a Bible Encyclopedia?

Not sold on TV!   

A Bible Dictionary or Bible Encyclopedia is a good second book to acquire.  Single volumes include Nelson's New Illustrated Bible Dictionary about $28, or New Unger's Bible Dictionary about $28, or New International Bible Dictionary about $23.  But wait! 

You may want a multi-volume set such as The International Standard Bible Encyclopedia, 4 Vols. about $70, or the Zondervan Pictorial Bible Encyclopedia, 5 Volumes about $100.  Some people may consider it a drawback that even if you buy the multi-volume sets, there's no vegetable chopper to keep as a free gift if you are dissatisfied.

KJV-based CBD'S Classic Reference Library, 4 Vols. About $50.

NIV-based NIV Bible Reference Collection, 3 Vols. About $60.

A Bible Dictionary makes a good second Bible study book.

Quiz: Is a Bible Dictionary like a Webster's Dictionary? 

a. Yes, both are boring. 
b. Yes, but a Bible Dictionary lists only the 9,000 words used to write the OT and the 6,000 words used to write the NT.
c. Yes, the ones with lots of pictures look impressive on the coffee table.
d. Yes, and both are unneeded if your spouse knows which animals were taken on the Ark in single pairs and which were taken in seven pairs and can spell well.  That's a good- spelling spouse, not 14 smart oxen.

Answer...