order_on = new Image()
             order_on.src = "images/order_on.gif"
             order_off = new Image()
             order_off.src = "images/order_off.gif"
			 
		     links_on = new Image()
             links_on.src = "images/links_on.gif"
             links_off = new Image()
             links_off.src = "images/links_off.gif"

 		     contact_on = new Image()
             contact_on.src = "images/contact_on.gif"
             contact_off = new Image()
             contact_off.src = "images/contact_off.gif"

 		     authors_on = new Image()
             authors_on.src = "images/authors_on.gif"
             authors_off = new Image()
             authors_off.src = "images/authors_off.gif"

			 books_on = new Image()
             books_on.src = "images/books_on.gif"
             books_off = new Image()
             books_off.src = "images/books_off.gif"
			 			 
 		     seminars_on = new Image()
             seminars_on.src = "images/seminars_on.gif"
             seminars_off = new Image()
             seminars_off.src = "images/seminars_off.gif"

			function chgimage(imgState,imgName){
				document[imgName].src = eval(imgName + "_" + imgState + ".src");
			}