function header(location, chapter, start, end)
{
	var url = location + chapter;
	if (start > 0 || end > 0)
	{
		url += '/';
		start = (start > 0) ? start : 0;
		end = (end > 0) ? end : 0;
		url += (start == end) ? start : start + '-' + end;
	}
	window.location = url;
	return false;
}