private BookData getSubset(int type, String value, BookData data){
		BookData subset;
		switch(type){
		case TITLE: subset=data.getByTitle(value);break;
		case AUTHOR: subset=data.getByAuthor(value);break;
		case PAGES:
			//Page range increments by 100
			int minPg=Integer.parseInt(value);
			int maxPg=minPg+99;
			subset=data.getByPageNum(minPg,maxPg);
			break;
		case YEAR: subset=data.getByPubYear(Integer.parseInt(value));break;
		case REVIEW:
			//review score increments by 1
			double minRev = Double.parseDouble(value);
			double maxRev = minRev + 1;
			subset = data.getByReview(minRev,maxRev);
			break;
		default: subset = null;
		}
		return subset;
	}