public int compare(Book o1, Book o2) {
	    	int num1=o1.getPubYear();
	        int num2=o2.getPubYear();
	        
	        if(num1>num2)
	        	return 1;
	        else if (num2>num1)
	        	return -1;
	        else
	        	return 0;
	    }