Perhaps you should try some spelling variations:
tinh thong » tinh thuong, trinh thong, tinh khong
tinh dung » trinh dung, tin dung, tinh quang
hieu suat » hieu luat, hieu qua
dung lan » dung luan, dung land, dung lam
van hieu » cao hieu
quan van » luan van, quan va, quan luan
van bien » van tien, van hien, vat bien
lan van » luan van, lang van, tan 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: (( tinh dung lan van hieu suat ) or ( tinh thong quan van bien so ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tinh dung lan van hieu suat ) OR ( tinh thong quan van bien so )).
• Adding a wildcard symbol may retrieve word variants: (( tinh dung lan van hieu suat ) or ( tinh thong quan van bien so ))*.