While there are others that are more in-depth, I've found these two to be good references that go beyond the basic level which most books stop at, while still being reasonable to understand.
For general history:
The Cigar Connoisseur: An Illustrated History and Guide to the World's Finest Cigars by Nathaniel Lande
For tobacco history:
Cuban Cigar Tobacco: Why Cuban Cigars Are the World's Best by Eumelio Espino Marrero