function random_imglink(){
  var myimages=new Array()
  //specify random images below. You can have as many as you wish
  myimages[1]="e-banner/Avastin and Malignant.gif"
  myimages[2]="e-banner/Frontiers in Anti-CanDD.gif"
  myimages[3]="e-banner/Omega3_Long_Chain.gif"
  //myimages[3]="e-banner/Casebook.gif"

  //specify corresponding links below
  var imagelinks=new Array()
  imagelinks[1]="http://benthamscience.com/ebooks/9781608051328/index.htm"
  imagelinks[2]="http://benthamscience.com/ebooks/9781608051618/index.htm"
  imagelinks[3]="http://benthamscience.com/ebooks/9781608051779/index.htm"
  //imagelinks[3]="http://www.java-scripts.net"

  var ry=Math.floor(Math.random()*myimages.length)

  if (ry==0)
     ry=1
    document.write('<a href='+'"'+imagelinks[ry]+'"'+' onclick="window.open(this.href); return false;"><img src="'+myimages[ry]+'" border=0></a>')
}

  random_imglink()