@Override
    public LinkedList<String> words() {
    	LinkedList<String> l = 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++) 
    		for (Occurrence occ : strTab.get(i))
    			if (occ.nbOcc <= 5)
    				l.add(occ.word);
    	
    	return l;
    }