What are the dates for the documents with both 'GV' type and 'SF' type expenses?
return documents ;return expenses of  #1 ;return types of  #1 ;return #1 where #3 is  'GV ;return #1 where #3 is  'SF ;return #1 of  both #4 and  #5 ;return dates of  #6
['select', 'project', 'project', 'comparative', 'comparative', 'intersection', 'project']