var selectednumber = 1;
function selectNumber(number) {
    var x = document.getElementById('ref_link_'+number);
    var y = document.getElementById('ref_link_'+selectednumber);
    var i = document.getElementById('ref_image_0');
    var j = document.getElementById('ref_image_'+number);
    if (i && j) i.src = j.src;
    if (y) y.style.fontWeight = 'normal';
    if (x) {
        x.style.fontWeight = 'bold';
        selectednumber = number;
    }
}