http://www.gnu.org
http://www.debian.org
http://www.linux.org
http://www.linux.com
http://www.linux.hr
http://gddistrowatch.tuwien.ac.at
http://www.postgresql.org
http://www.mojCD.com
ftp://sunsite.unc.edu/pub/Linux/docs/HOWTO
http://www.doc.ic.ac.uk/~wjk/UnixIntro
http://emoglen.law.columbia.edu/publications/dcm.html