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

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 tang van hieu suat ) or ( tinh quang uan van ((kien soat) or (dien (hoa OR khoa))) ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tinh dung tang van hieu suat ) OR ( tinh quang uan van ((kien soat) OR (dien (hoa OR khoa))) )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( tinh dung tang van hieu suat ) or ( tinh quang uan van ((kien soat) or (dien (hoa OR khoa))) ))".
• Adding a wildcard symbol may retrieve word variants: (( tinh dung tang van hieu suat ) or ( tinh quang uan van ((kien soat) or (dien (hoa OR khoa))) ))*.