This little user space thread library was derived from Stephen Crane's
REX, described in:

  S. Crane, The REX Lightweight Process Library, Department of
  Computing, Imperial College of Science, Technology and Medicine,
  London, 1993.

The original code may still float around on the web.  Try to search
for lwp-0.1.tar.gz.

This is its original copyright notice:

Copyright (C) 1991-3 Stephen Crane.

This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public
License as published by the Free Software Foundation; either
version 2 of the License, or (at your option) any later version.

This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
Library General Public License for more details.

You should have received a copy of the GNU Library General Public
License along with this library; if not, write to the Free
Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

author: Stephen Crane, (jsc@doc.ic.ac.uk), Department of Computing,
Imperial College of Science, Technology and Medicine, 180 Queen's
Gate, London SW7 2BZ, England.