function hideDivs(exempt)
{
  if (!document.getElementsByTagName) return null;
  if (!exempt) exempt = "";
  var divs = document.getElementsByTagName("div");
  for(var i=0; i < divs.length; i++)
  {
    var div = divs[i];
    var id = div.id;
    if ((id == "bookBoxArt1") 
    || (id == "bookBoxArt2") 
    || (id == "bookBoxArt3")
    || (id == "bookBoxArt4"))
    {
    	if (id != exempt) {
     	div.className = "bookBoxArt hidden";
    	}
    }
  }
}
function show(what)
{
  if (!document.getElementById) return null;
  showWhat = document.getElementById(what);
  showWhat.className = "bookBoxArt";
  hideDivs(what);
}