Perhaps you should try some spelling variations:
quang quan » quang tuan, quang uan, quan quan
hieu suat » hieu luat, hieu qua
tinh dung » trinh dung, tin dung, tinh huong
hien soat » thien hoat, kiem soat, bien soan
quan van » luan van, quan va, quan luan
van hien » van hieu, van tien
lan van » luan van, lang van, san van
tan van » tran van, tang van, luan 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 ((lan van) OR (tan van)) hieu suat ) or ( tinh quang quan van hien soat ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tinh dung ((lan van) OR (tan van)) hieu suat ) OR ( tinh quang quan van hien soat ))*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( tinh dung ((lan van) OR (tan van)) hieu suat ) or ( tinh quang quan van hien soat ))*".