Perhaps you should try some spelling variations:
tieu sach » chieu sach, dien sach, te sach
hanh manh » hanh mang, lanh manh, hoang manh
dang cong » dung cong
hang cong » hang nong, bang cong, thanh cong
manh cua » doanh cua, ban cua
van toan » van tuan, van tan, van thanh
dan than » dan chan, ban than, van than

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: theo tieu sach - hanh manh cua ((dang cong) OR (hang cong)) ((van toan) OR (dan than)) cao~.
• Adding a wildcard symbol may retrieve word variants: theo tieu sach - hanh manh cua ((dang cong) or (hang cong)) ((van toan) or (dan than)) cao*.