Perhaps you should try some spelling variations:
thien hach » thien thanh, hien hanh
theo sach » thuoc sach, te sach, theo lich
canh manh » lanh manh, canh tranh, cach mang
dang cong » dung cong
manh cua » doanh cua, ban cua
cua dang » cua cong, cua ban
dan toan » van toan, manh toan, xuan toan
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: hoc ((theo sach) OR (thien hach)) - canh manh cua dang cong ((dan toan) OR (dan than)) cao~.
• Adding a wildcard symbol may retrieve word variants: hoc ((theo sach) or (thien hach)) - canh manh cua dang cong ((dan toan) or (dan than)) cao*.