function btopLink() {
  var myWHeight = 0, myHeight = 0;
  if( typeof( window.innerHeight ) == 'number' ) {
    //Non-IE
    myWHeight = window.innerHeight;
    myHeight = document.body.clientHeight;
  } else if( document.documentElement && document.documentElement.clientHeight ) {
    //IE 6+ in 'standards compliant mode'
    myWHeight = document.documentElement.clientHeight;
    myHeight = document.body.clientHeight;
  } else if( document.body && document.body.clientHeight ) {
    //IE 4 compatible
    myWHeight = document.body.clientHeight;
    myHeight = document.documentElement.clientHeight;
  }
  if ((myHeight-30) > myWHeight) {
  	document.write('<p style="text-align:right"><a href="#">back to top</a></p>\n');
//  	document.write('<p style="text-align:right"><a href="' + location.href + '">back to top</a></p>\n');
  }
  //window.alert( 'Window Height = ' + myWHeight + ' Doc Height = ' + myHeight );
}