Database: cre_Doc_Tracking_DB
Question: Find the document type name of the document named "How to read a book".
SQL:
SELECT T2.document_type_name FROM All_documents AS T1 JOIN Ref_document_types AS T2 ON T1.document_type_code  =  T2.document_type_code WHERE T1.document_name  =  "How to read a book"