function changePage(divId) {	

	switch (divId) {
		case "lib1":
		document.getElementById("lib1").style.display = "block";
		document.getElementById("lib2").style.display = "none";
		document.getElementById("lib3").style.display = "none";
		break;
		
		case "lib2":
		document.getElementById("lib1").style.display = "none";
		document.getElementById("lib2").style.display = "block";
		document.getElementById("lib3").style.display = "none";
		break;
		
		case "lib3":
		document.getElementById("lib1").style.display = "none";
		document.getElementById("lib2").style.display = "none";
		document.getElementById("lib3").style.display = "block";
		break;
		
		default:
		document.getElementById("lib1").style.display = "block";
		document.getElementById("lib2").style.display = "none";
		document.getElementById("lib3").style.display = "none";
	}
	
}