This opening book is in the public domain. It was put together and
cleaned up by  Stuart Cracraft <cracraft@earthlink.net>  and  Simon
Waters <simon@wretched.demon.co.uk> . Stuart wrote the following in
email, when asked about copyright.

  I personally built the GNU Chess book from a large set of FREE
  game collections from the University of Pittsburgh chess server.
  These are NOT copyrighted and are PUBLIC. I also wrote the code
  for the GNU Chess book without any reference at all to any other
  author.

  It is GNU Chess code and PUBLIC book that is non-copyrightable.

  --Stuart

Note that all the code is in gnuchess, so this package itself is
purely public domain.