List all the titles of the Spanish books published by Alfaguara.
"Spanish" is the language_name; 'Alfaguara' is the publisher_name
SELECT T2.title FROM book_language AS T1 INNER JOIN book AS T2 ON T2.language_id = T1.language_id INNER JOIN publisher AS T3 ON T3.publisher_id = T2.publisher_id WHERE T1.language_name = 'Spanish' AND T3.publisher_name = 'Alfaguara' GROUP BY T2.title