http://www.bell-labs.com/history/unix/wars.html

http://pt.wikipedia.org/wiki/Posix

    http://www.groklaw.net/article.php?story=20050601125916588

http://pt.wikipedia.org/wiki/Single_UNIX_Specification

http://pavg.stanford.edu/rapide/examples/xopen

http://www.faqs.org/docs/artu/index.html

http://www.opengroup.org/

http://equipe.nce.ufrj.br/gabriel/sofix.html

http://en.wikipedia.org/wiki/UNIX

http://www.faqs.org/docs/artu/ch02s01.html

http://snap.nlc.dcccd.edu/learn/drkelly/hst-hand.htm