function chgImg(aID, aSrc) {
  document.getElementById(aID).src=aSrc;
}
var iOnLoad = new Image();
iOnLoad.src = "images/introw.gif";
iOnLoad.src = "images/pricew.gif";
iOnLoad.src = "images/referencew.gif";
iOnLoad.src = "images/articlew.gif";
iOnLoad.src = "images/certificatew.gif";
iOnLoad.src = "images/photosw.gif";