private String personToString(Person person) {
		String result="";
		result+= person.getId() + ";";
		result+= person.getName() + ";" + person.getSurname() + ";" +
				 person.getBirth_day() + "-" + person.getBirth_month() + "-" 
				 + person.getBirth_year(); 
		result+= ";"+person.getPesel();
		result+= ";"+person.getSalary();
		for (NumberType type : NumberType.values())
			result+= ";" + person.getNumber(type);
		return result;
	}