Perhaps you should try some spelling variations:
theo chiet » theo chieu, thep thiet
chiet tach » chieu sach
canh tinh » manh tinh, canh tranh, nhanh tinh
hanh tinh » hanh trinh, nhanh tinh, thanh tinh
dung cong » dung trong
tan toan » tan tran, van toan, dan toan
tap toan » tap doan, tap quan, bai toan

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 chiet tach - ((canh tinh) OR (hanh tinh)) ung dung cong ((tan toan) OR (tap toan)) cau~.
• Adding a wildcard symbol may retrieve word variants: theo chiet tach - ((canh tinh) or (hanh tinh)) ung dung cong ((tan toan) or (tap toan)) cau*.