public Set<Bill> removeBillByDate(Set<Bill> b, Calendar c) {

		Iterator<Bill> bIt = b.iterator();
		Set<Bill> bills = b;
		while (bIt.hasNext()) {
			Bill bAux = bIt.next();
			if ((bAux.getDate().get(Calendar.MONTH) == c.get(Calendar.MONTH))
					&& ((bAux.getDate().get(Calendar.YEAR) == c
							.get(Calendar.YEAR)))) {
				bIt.remove();
			}

		}
		return bills;
	}