public boolean isCurrentlyBorrowed(String materialID, Calendar startDate,
			Calendar endDate) {

		for (Loan l : this.unreturnedLoans) {
			if ((l.getStartDate().after(startDate) && l.getStartDate().before(
					endDate))
					|| (l.getEndDate().after(startDate) && l.getEndDate()
							.before(endDate))
					&& l.getListOfMaterials().contains(materialID)) {
				return true;
			}
		}

		return false;
	}