[Boost-users] boost::gregorian::months : access value / serialize

Hallo, I've to serialize the value of months into a databse. This requires to access the value (amount of months) stored inside of boost::gregorian::months. How can I access the internal value (nothing found in the docu)? If this is not possible which boost::date_time type should I in order to store a datetime duration consisting of the pair years and months (Oracle database type INTERVAL YEAR TO MONTH)? Regards, Oliver