Database: tracking_grants_for_research
Question: For grants with both documents described as 'Regular' and documents described as 'Initial Application', list its start date.
SQL:
SELECT T1.grant_start_date FROM Grants AS T1 JOIN Documents AS T2 ON T1.grant_id  =  T2.grant_id JOIN Document_Types AS T3 ON T2.document_type_code  =  T3.document_type_code WHERE T3.document_description  =  'Regular' INTERSECT SELECT T1.grant_start_date FROM Grants AS T1 JOIN Documents AS T2 ON T1.grant_id  =  T2.grant_id JOIN Document_Types AS T3 ON T2.document_type_code  =  T3.document_type_code WHERE T3.document_description  =  'Initial Application'