Perhaps you should try some spelling variations:
quang quan » quang tuan, quang uan, quan quan
thien hoat » trien hoat, thien thuat, tien hoa
hieu suat » hieu luat, hieu qua
hien soat » kiem soat, bien soan, hien luat
dun nang » dung nang, den nang, luan nang
nang van » dang van, tang van, lang van
van hieu » cao hieu
quan van » luan van, quan va, quan luan
tin dun » tin dung, tin don, tinh dung

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( tin dun nang van hieu suat ) or ( tinh quang quan van ((hien soat) or (thien hoat)) ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tin dun nang van hieu suat ) OR ( tinh quang quan van ((hien soat) OR (thien hoat)) )).
• Adding a wildcard symbol may retrieve word variants: (( tin dun nang van hieu suat ) or ( tinh quang quan van ((hien soat) or (thien hoat)) ))*.