function Page_onkeydown(event) {
    var id = false;
    event = event || window.event;
    var key = event.keyCode;
    if (event.ctrlKey) {
        var tag = (event.target || event.srcElement).tagName;
        if (tag != 'INPUT' && tag != 'TEXTAREA') {
            if (key == 37) {
                id = document.getElementById('page_previous');
            }
            if(key == 39) {
                id = document.getElementById('page_next');
            }
            if (id) {
                location.href = id.href;
            }
        }
    }
}