Perhaps you should try some spelling variations:
luong tai » dung tai, luong va
hieu soat » hieu suat, hieu hoat, hieu luat
tinh dung » trinh dung, tin dung, tinh quang
dong tai » dung tai, cong tac, hang tai
van hieu » cao hieu
dung dam » dung dat, dung lam, dung dan
van hien » van tien
hien hoa » hien khoa, dien hoa, tien hoa
dam van » dao van, nam van, pham van

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( tin ((dong tai) OR (luong tai)) van hieu soat ) or ( tinh dung dam van hien hoa ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tin ((dong tai) OR (luong tai)) van hieu soat ) OR ( tinh dung dam van hien hoa ))*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( tin ((dong tai) OR (luong tai)) van hieu soat ) or ( tinh dung dam van hien hoa ))*".