User:Roaming/monobook.js

function externISBN { for (var i = 0; i < document.links.length; i++) {               var ln = document.links[i].href.match(/isbn=(.*)/); if (ln) { document.links[i].href='http://www.a9.com/isbn%20'+RegExp.$1; }   }

}

addOnloadHook(externISBN);