Write SQL query to solve given problem: List all paper ID and its class type with more than 20 cited words.. Keep the solution inside sql tag ```sql [SQL-Query] ```
SELECT DISTINCT T1.paper_id, T1.class_label FROM paper AS T1 INNER JOIN content AS T2 ON T1.paper_id = T2.paper_id GROUP BY T2.paper_id, T1.class_label HAVING COUNT(T2.word_cited_id) > 20