Perhaps you should try some spelling variations:
tran hoang » tran hong, quan hoang, tran quang
tinh dung » trinh dung, tinh quang, tinh huong
hieu soat » hieu hoat, hieu luat, kiem soat
hieu suat » hieu luat, hieu qua
dung dat » dung va, dung tai
van tran » van trang, van tranh, van tuan
dat van » dao van, dat va, dam van
luan » quan, lan

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

• The words AND, OR and NOT may confuse the search; try adding quotes: "(( tinh dung luan van ((hieu soat) OR (hieu suat)) ) OR ( tin dung dat van tran hoang ))~".
• Adding a wildcard symbol may retrieve word variants: (( tinh dung luan van ((hieu soat) OR (hieu suat)) ) OR ( tin dung dat van tran hoang ))*.