SELECT p.firstname, p.lastname, p.emailaddress
FROM Persons p
WHERE organizationnr IN (
   SELECT organization_id
   FROM Events
   WHERE MONTH(EventDate) = 2 AND YEAR(EventDate) = 2009
)
ORDER BY p.lastname, p.firstname;

SELECT organization_id
FROM Events
WHERE MONTH(EventDate) = 2 AND YEAR(EventDate) = 2009