Perhaps you should try some spelling variations:
trinh quan » trinh luat, trinh han
doan hieu » doanh hieu, doan dieu, doan thien
hieu suat » hieu luat, hieu qua
quang tan » quang tuan, quang tran, quang toan
quan van » luan van, quan va, quan luan
van doan » van doanh, van toan, van hoan
van bien » van tien, van hien, vat bien
tan van » tran van, tang van, luan van
bien so » bien doi

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( trinh quan van doan hieu suat ) or ( tinh quang tan van bien so ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( trinh quan van doan hieu suat ) OR ( tinh quang tan van bien so ))*.