WEBGRAFIA

• http://www.sc.ehu.es/sqwpolim/FISICAII/P5.pdf
• http://www.youtube.com/watch?v=-gA_hHWluAQ
• http://www.youtube.com/watch?v=nkInOdBAQpE&feature=relmfu
• http://www.heurema.com/PDF57.htm