Hard to write a book on iq when there isn't even a scientific consensus what intelligence is. The content of The Bell Curve has been refuted by uncountable politically unbiased scientists and psychologists.
The Bell Curve and other print books are the highest quality sources, with footnotes to scientific studies. The black-white IQ gap is one of the best documented phenomenons in the social sciences. I'm surprised that you haven't heard of it. Search "Black-white IQ gap" and you will find many charts and articles, even though Google tends to suppress this type of information.
