function random_imglink(){
  var myimages=new Array()
  //specify random images below. You can have as many as you wish
    myimages[1]="e-banner/Frontiers in Drug Design & Discovery Volume 1.gif"
	myimages[2]="e-banner/Frontiers in Drug Design & Discovery Volume 2.gif"
	myimages[3]="e-banner/Frontiers in Drug Design & Discovery Volume 3.gif"
	myimages[4]="e-banner/Frontiers in Drug Design & Discovery Volume 4.gif"
	myimages[5]="e-banner/Pathogenic Escherichia coli in Latin America.gif"
	
  //specify corresponding links below
  var imagelinks=new Array()
   	imagelinks[1]="http://benthamscience.com/ebooks/9781608051991/index.htm"
	imagelinks[2]="http://benthamscience.com/ebooks/9781608052004/index.htm"
	imagelinks[3]="http://benthamscience.com/ebooks/9781608052011/index.htm"
	imagelinks[4]="http://benthamscience.com/ebooks/9781608052028/index.htm"
	imagelinks[5]="http://benthamscience.com/ebooks/9781608051922/index.htm"
	
  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()