There was a lot of criticism of Haley when the book and the TV series came out for writing "faction", fact and fiction intermingled without attribution. It was not so much that he didn't do a lot of genuine research as that he filled in the blanks to make a good story. There was particular skepticism about his tracing all the way back to Africa, especially since it is so notoriously hard to do. As I recall, he claimed to have located his original African ancestor by "oral history," matching a name in his own family tradition with a name in a memorized oral history in Africa (sorry, I'm drawing a blank on the details; it has been about 20 years since I read the book). I don't know as anyone ever was able to confirm the African oral history he was relying on. That's the kind of bibliography that's hard to verify.