Perhaps you should try some spelling variations:
theo chiet » theo chieu, thep thiet
chiet tach » chieu sach
khong cong » thong cong, chong cong, khong con
khong cang » thong cong, hong bang, khong dung
hanh tinh » hanh trinh, nhanh tinh, thanh tinh
tinh cua » trinh cua, sinh cua, tinh chat
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: theo chiet tach - hanh tinh cua ((khong cong) OR (khong cang)) ((dan toan) OR (dan than)) cau~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "theo chiet tach - hanh tinh cua ((khong cong) OR (khong cang)) ((dan toan) or (dan than)) cau~".
• Adding a wildcard symbol may retrieve word variants: theo chiet tach - hanh tinh cua ((khong cong) OR (khong cang)) ((dan toan) or (dan than)) cau*.