Perhaps you should try some spelling variations:
chieu sach » chinh sach, chiet tach, chieu sang
thanh tran » thanh trang, thanh toan, thanh tra
quang dung » quang trung, ung dung, cuong dung
hieu cach » hieu cac, hieu ca, biet cach
ban toan » bai toan, ban than, bao toan
van toan » van tuan, van tan, van thanh

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: hoc ((hieu cach) OR (chieu sach)) - thanh tran quang dung trong ((ban toan) OR (van toan)) ban~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((hieu cach) or (chieu sach)) - thanh tran quang dung trong ((ban toan) OR (van toan)) ban~".
• Adding a wildcard symbol may retrieve word variants: hoc ((hieu cach) or (chieu sach)) - thanh tran quang dung trong ((ban toan) OR (van toan)) ban*.