Perhaps you should try some spelling variations:
chau tinh » cuu tinh, ha tinh, cua tinh
hanh han » hanh nhan, hanh phan, hanh san
cong dan » cong tan, huong dan, cong dong
cong san » cong tac
toan cau » toan cao, toan ban, toan tap
va tinh » may tinh
va tong » va thong, va tuong, va trong
han va » hang va, hanh va, nhan va

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: hoc ((chau tinh) or (va tinh)) - hanh han va tong ((cong dan) OR (cong san)) toan cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((chau tinh) OR (va tinh)) - hanh han va tong ((cong dan) OR (cong san)) toan cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((chau tinh) or (va tinh)) - hanh han va tong ((cong dan) OR (cong san)) toan cau".
• Adding a wildcard symbol may retrieve word variants: hoc ((chau tinh) or (va tinh)) - hanh han va tong ((cong dan) OR (cong san)) toan cau*.