public Book book_search_lib() throws Exception{ 
		int choice=0, y=0;
		//ִܿµ
		//ԷѴܾԵȸ絵
		String newtitle;
		int ISBN = 0;
		Scanner scan = new Scanner(System.in);
		System.out.print("1. or 2.ISBN  (ȣ ) : ");
		choice= scan.nextInt(); 

		if(choice==1)
		{
			System.out.println("*******************************************************************");
			System.out.print(":");
			newtitle = scan.next();

			if(getequal2(newtitle)==1)
			{
				print(newtitle);
				System.out.println("*******************************************************************");
				System.out.println("˻ѴܾѸå̰˻Ǿϴ!");
				System.out.println("*******************************************************************");
				//ISBN ˻ϴ Լ 
				Book result_book = search_ISBN();
				if(result_book ==null){
					return null;
				}else{
					return result_book;
				}
			}else {
				System.out.println("˻ġϴ°ϴ!");
				System.out.println("*******************************************************************");
				return null;
			}
		}
		if(choice==2){
			System.out.println("*******************************************************************");
			//ISBN ˻ϴ Լ 
			Book result_book =search_ISBN();
			if(result_book ==null){
				return null;
			}else{
				return result_book;
			}
		}
		return null;

	}