Many of the files here are

Copyright (C) 1993, 1994, John Kilburg.

See src/copyright.h for details.  Basically, you can use this as long
as you don't sell it (i.e. you can use it for internal business,
educational, or personal use).

The files in libhtmlw/ are

Copyright (C) 1993, Board of Trustees of the University of Illinois

See the top of libhtmlw/HTML.h for details.

There is code for strstr() in src/util.c that is

Copyright (c) 1988-1993 The Regents of the University of California.
All rights reserved.

Check out the code in xloadimage/ for details copyright information.