You might want to use the following preprint of an
appendix of a book that is not the ISO core standard:
ISO Prolog: A Summary of the Draft Proposed Standard.
Michael A. Covington, 1993
http://www.uv.es/fbarber/prolog/isoprolog94_ps.Z
http://www.dropbox.com/s/kr1pbrfc1kqzdpq/isoprolog94_ps.Z
It is much shorter than the full ISO standard, but
it informally predates and covers almost the same.
