Correct way to cite a book in a thesis
You can only put a book or paper in the bibliography if you have cited it in the text, either via a quote or by citing its argument[s], theory/ies, etc.
If it's just generally deepened your understanding and you do not quote it or cite its argument[s] it cannot be included in the bibliography. That said, in such a case it can be very easy to work in a citation from it anyway, even if it's just a few words.