What are the publishers who have published a book in both 1989 and 1990?
SELECT publisher FROM book_club WHERE YEAR  =  1989 INTERSECT SELECT publisher FROM book_club WHERE YEAR  =  1990
SELECT publisher FROM book_club WHERE YEAR  =  1989 INTERSECT SELECT publisher FROM book_club WHERE YEAR  =  1990
[{'Publisher': 'Alyson'}, {'Publisher': 'Banned Books'}]