Use Search Almost Everything to find both the print books in the library and 1000s of eBooks
Your historical person may have a "Research Starter" which is an entry from a recent encyclopedia. It will appear at the top of the results list after the intitial search. This is a great starting point to understanding your person and their contribution to the field.
Do your search and then check off the box "Books" under "Source Types" in the left column to narrow your results to books - both print and eBooks. If you want just eBooks then choose that box instead.