function period(){
	var ul = document.getElementById('periods');
	if (!ul){return;}
	var div = document.getElementsByTagName('div');
	var li = [];
	var year = [];
	
	for (var i=0;i<div.length;i++){
		if ((" "+div[i].className+" ").indexOf(' year ') != -1){year.push(div[i]);}
	}
	li = ul.getElementsByTagName('li')
	for (var i=0;i<li.length;i++){
		li[i].onclick = function(e){
			stopEvent(e);
			
			for (var j=0;j<li.length;j++){
				li[j].className = li[j].className.replace(/\bactive\b/gi,"");
			}
			this.className += " active";
			for (var j=0;j<year.length;j++){
				year[j].style.display = 'none';
				if ((" "+year[j].id+" ").match(" "+this.id+" ")){
					year[j].style.display = 'block';
				}
			}
			scrollBy(0, 10000);
		}
	}
}
function stopEvent(e){
	var event = e || window.event;
	event.preventDefault ? event.preventDefault() : event.returnValue = false;
}
superOnload(period);