@Override
    public LinkedList<String> words() {
    	LinkedList<String> ll = new LinkedList<String>();
    	
    	// Return only the words appearing with low frequencies. Here words with less than 5 occurrences
    	// in the text.
    	for (int i = b; i <= 32; i++){
    		HashMap<String, Integer> t = strTab.get(i);
    		for (String s : t.keySet()){
    			int occ = t.get(s);
    			if (occ <= 5)
    				ll.add(s);
    		}
    	}
    	
    	return ll;
    }