Perhaps you should try some spelling variations:
thanh tran » thanh trang, thanh toan, thanh tra
quang dung » quang trung, ung dung, cuong dung
dung cong » dung trong
hieu cua » hieu qua, dieu cua, bieu cua
ban toan » bai toan, ban than, bao toan
van toan » van tuan, van tan, van thanh
hieu ca » hieu cac, hieu va, hieu xa

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

• If you are trying to use Boolean operators, they must be ALL CAPS: doc ((hieu ca) OR (hieu cua)) - thanh tran quang dung cong ((ban toan) OR (van toan)) tap~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc ((hieu ca) or (hieu cua)) - thanh tran quang dung cong ((ban toan) OR (van toan)) tap~".
• Adding a wildcard symbol may retrieve word variants: doc ((hieu ca) or (hieu cua)) - thanh tran quang dung cong ((ban toan) OR (van toan)) tap*.