$(document).ready(function(){
if (!jQuery._history) {

/* history back
----------------------------------------------------------- */

	// change image
	$("img.history").each(function(){
			$(this).attr("src", $(this).attr("src").replace(/^(.+)_history_(.+)$/, "$1_$2"));
			$(this).show();
			$(this).parents(":hidden").show();
			$(this).click(function(event){
				history.back();
				event.preventDefault();
			});
	});

	jQuery._history = true;
}
});