Sources+cited

Sources cited


 * http://www.webelements.com/webelements/elements/text/V/key.html
 * http://www.atsdr.cdc.gov/tfacts58.html
 * http://education.jlab.org/itselemental/ele023.html
 * http://www.theodoregray.com/PeriodicTable/Elements/023/#sample7