chemistry.about.com... http://chemistry.about.com/od/elementfacts/a/oxygen.htm http://chemistry.about.com/od/elementfacts/a/oxygen.htm Oxygen Facts - Periodic Table of the Chemical Elements http://chemistry.about.com/od/elementfacts/a/oxygen.htm http://chemistry.about.com/od/elementfacts/a/oxygen.htm Oxygen Facts - Periodic Table of the Chemical Elements "Oxygen Facts - Periodic Table of the Chemical Elements" "Oxygen Facts - Periodic Table of the Chemical Elements"