public List<SingleCounter> extractKeyNouns (Documents docs, int n) {
    	Counter c = new Counter();
    	
    	for (Document d : docs.documents) {
    		for (Sentence s : d.sentences) {
    			Phrases p = s.phrases;
    			for (int idx = 0; idx < p.size(); idx++) {
    				 for (String term : p.getNouns(idx)) {
    					 c.add(term);
    				 }
    			}
    		}
    	}
    	
    	return c.topN(n);
    }