Perhaps you should try some spelling variations:
chieu sach » chinh sach, chiet tach, chieu sang
thanh tung » thanh cong
hieu sach » hieu cach, dien sach, hieu cac
nang nong » nang song, hang nong, nang dong
manh toan » thanh toan, anh tuan, tinh toan
dan toan » van toan, dan than, xuan toan
tung va » trung va, tuong va, dung va
va nang » van nang, da nang, cam nang

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 sach) OR (chieu sach)) - thanh tung va nang nong ((dan toan) OR (manh toan)) cau~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc ((hieu sach) OR (chieu sach)) - thanh tung va nang nong ((dan toan) or (manh toan)) cau~".
• Adding a wildcard symbol may retrieve word variants: doc ((hieu sach) OR (chieu sach)) - thanh tung va nang nong ((dan toan) or (manh toan)) cau*.