The book sites many sources there are 28 pages listing the sources of information used to compile the book. There are state libraries as well as the Library of Congress, vital records bureaus, US censuses, federal military databases, SS death indexes, marriage records, patriotic society databases, federal immigration records and more. Enough reputable sources for you?
The David Robert confederacy thing was a footnote and was stated that it was not fully substantiated, that birth and death were not certain, which is why I stated "possibly" and not that he "was". I have not finished all my research and thought that here was a good place to exchange information not get nit-picked.
Thank you for your reply.