Question: Which country with a city with a population between 50,000 and 300,000 inhabitants and which is a member of an organization established between 03/01/1991 and 04/30/1991 is also a member of the EBRD?
SQL: SELECT T2.Country FROM country AS T1 INNER JOIN isMember AS T2 ON T1.Code = T2.Country INNER JOIN organization AS T3 ON T3.Country = T2.Country INNER JOIN city AS T4 ON T4.Country = T3.Country WHERE T3.Abbreviation = 'EBRD' AND T4.Population BETWEEN 50000 AND 300000 AND T3.Established BETWEEN '1991-01-31' AND '1991-04-30'