If you are interested in the US copyright, you can go to:
http://cocatalog.loc.gov/cgi-bin/Pwe...cal&PAGE=First
and look up books after 1977 by name or title. In the listing is the nature of the copyright claim. That may help you decide if you can use the source. Often it is new front matter and end matter, which you can be careful to skip.
In this case, they may have added a table of contents and index which you will probably have to skip. But indexes are not so useful in an ebook because the pages keep changing and if the ebook process creates a e table of contents I can't see how that would be a problem anyone could sue over.