Perhaps you should try some spelling variations:
thuyet tach » thuyet mach, thuyet hach, thuyet xac
hoc thuyet » hoc chuyen
thanh tung » thanh cong
tung cac » dung cac, vung cac, cung cac
cong dan » cong san, cong tan, cong dong
than cau » toan cau, phan cau, than cap
cac van » cac dan

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc thuyet tach - thanh tung cac van ((cong dan) or (huong dan)) than cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc thuyet tach - thanh tung cac van ((cong dan) OR (huong dan)) than cau.
• Adding a wildcard symbol may retrieve word variants: hoc thuyet tach - thanh tung cac van ((cong dan) or (huong dan)) than cau*.