http://www.alleslinux.com/prog_pics/kde-lnxhelp.png

http://www.amazon.com/Apple-Mac-Version-10-5-1-Leopard/dp/B000FK88JK

http://www.apple.com/es/macosx

http:/www.exa.unne.edu.ar/depar/areas/informatica/SistemasOperativos/MonogSO/LINUX99.htm

http://www.cosaslibres.com/plinuxmk.htm

http://firstpartners.net/kb/images/2/21/Red-hat-splash-screen.jpg

http://www.maestrosdelweb.com/editorial/historia-y-evolucion-del-sistema-operativo-mac-os/