info_visible = false;
function showAdditionalInfo(){
    info = document.getElementById('more_info');
    info_text = document.getElementById('link_info');
    if(info_visible) {
        info.style.display = 'none';
        info_text.innerHTML = '+ info';
    } else {
        info.style.display = 'block';
        info_text.innerHTML = '- info';
    }
    info_visible = !info_visible;
}