var amazonWin;

function amazonRefer(s) {

    var ix = s.indexOf("ASIN");
    if (ix >= 0) {
        s = s.substring(ix+5);
    }
    ix = s.indexOf('/');
    if (ix >= 0 && ix < 5) {
        s = s.substring(ix);
    }
    ix = s.indexOf('/');
    if (ix > 0) {
        s = s.substring(0, ix);
    }

    var url = "http://www.amazon.co.uk/exec/obidos/ASIN/" +s +"/ingenotechltd";
    if (!amazonWin) {
        amazonWin = window.open(url, "amazonWin");
    } else {
        amazonWin.navigate(url);
    }
    return false;
}