question: What are the names of documents that have both one of the three most common types and one of three most common structures?
#1 return documents 
#2 return type of   #1 
#3 return structures of   #1 
#4 return three  most common #2 
#5 return three  most common #3 
#6 return #1 in both #4 and #5 
#7 return names of   #6