function gomonth(dir) { 
    var text = self.location.href;
    var pos = text.indexOf('month');
    var num = text.substring(pos+5,pos+7) - 0 + dir;
    num = (num < 10) ? "0" + num : ( (num < 100) ? num : num);
    window.location.href = text.substring(0,pos+5) +
                           num +
                           text.substring(pos+7,text.length);
}