function displayCitations() {
  if (!document.getElementsByTagName || !document.createElement || !document.createTextNode) return false;
// get all the blockquotes
  var quotes = document.getElementsByTagName("blockquote");
// loop through all the blockquotes
  for (var i=0; i<quotes.length; i++) {
// if there is no cite attribute, continue the loop
    if (!quotes[i].getAttribute("cite")) continue;
// store the cite attribute
    var url = quotes[i].getAttribute("cite");
// get all the element nodes in the blockquote
    var quoteChildren = quotes[i].getElementsByTagName('*');
// if there are no element node, continue the loop
    if (quoteChildren.length < 1) continue;
// get the last element node in the blockquote
    var elem = quoteChildren[quoteChildren.length - 1];
// create the markup
    var link = document.createElement("a");
    var link_text = document.createTextNode("source");
    link.appendChild(link_text);
    link.setAttribute("href",url);
    var superscript = document.createElement("sup");
    superscript.appendChild(link);
// add the markup to the last element node in the blockquote
    elem.appendChild(superscript);
  }
}
window.onload = displayCitations;