Give the publisher's name of the books authored by Alan Lee.
"Alan Lee" is the author_name; publisher's name refers to publisher_name
SELECT T4.publisher_name FROM book AS T1 INNER JOIN book_author AS T2 ON T1.book_id = T2.book_id INNER JOIN author AS T3 ON T3.author_id = T2.author_id INNER JOIN publisher AS T4 ON T4.publisher_id = T1.publisher_id WHERE T3.author_name = 'Alan Lee' GROUP BY T4.publisher_name