Perhaps you should try some spelling variations:
tinh dung » trinh dung, tin dung, tinh huong
dung lang » dung dang, dung nang, dung land
hieu suat » hieu luat, hieu qua
quang uan » quang tuan, quang ban, quang tran
kien soat » kiem soat, bien soan, kien hoa
lang van » dang van, tang van, hoang van
van hieu » cao hieu
uan van » luan van, quan van, tan van
hoa » khoa

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( tinh dung lang van hieu suat ) or ( tinh quang uan van ((kien soat) or (dien hoa)) ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tinh dung lang van hieu suat ) OR ( tinh quang uan van ((kien soat) OR (dien hoa)) )).
• Adding a wildcard symbol may retrieve word variants: (( tinh dung lang van hieu suat ) or ( tinh quang uan van ((kien soat) or (dien hoa)) ))*.