The title should read:
E-book, e-book, ebook or eBook
I’m sure we’re not the only ones confused.
The Library of Congress uses ebook.
Amazon uses eBook.
Apple uses e-book.
I could go on, but there doesn’t seem to be any real standardization of the word.
I’ll leave you with this caveat:
Email used to be commonly spelled “e-mail”—The New York Times only dropped that hyphen in 2013 after everyone else had.
So, my conclusion is spell it however you want, but be consistent.
For us, we’ll be using ebook.