Perhaps you should try some spelling variations:
tinh huong » dinh huong, anh huong
huong luan » huong lan, cuong luan, huong loan
hieu soat » hieu suat, hieu hoat, hieu luat
tien soat » trien hoat, thien hoat, kiem soat
dang van » hoang van, hang va
van tien » toan tien, van hieu, van tuan
tan van » tran van, tang van, tan tran

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (( tinh quang ((tan van) OR (dang van)) hieu soat ) or ( tinh huong luan van tien soat ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tinh quang ((tan van) OR (dang van)) hieu soat ) OR ( tinh huong luan van tien soat )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( tinh quang ((tan van) OR (dang van)) hieu soat ) or ( tinh huong luan van tien soat ))".
• Adding a wildcard symbol may retrieve word variants: (( tinh quang ((tan van) OR (dang van)) hieu soat ) or ( tinh huong luan van tien soat ))*.