Perhaps you should try some spelling variations:
duong quan » duong quang, duong qua, luong quan
trinh dun » trinh dung, trinh dan, trinh den
hieu suat » hieu luat, hieu qua
dun nang » dung nang, den nang, luan nang
nang van » dang van, tang van, lang van
van hieu » cao hieu
tri dien » tri kien, trinh dien, tri chien
dien co » dien cho, dien o, dien cu

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( trinh dun nang van hieu suat ) or ( dinh duong quan tri dien co ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( trinh dun nang van hieu suat ) OR ( dinh duong quan tri dien co ))*.