Perhaps you should try some spelling variations:
thuyet tach » thuyet mach, thuyet hach, thuyet xac
hoc thuyet » hoc chuyen
trong thoi » trong tho, trong trot, trong thu
trong thi » trong thu, trong tho, trong thuc
cong dan » cong tan, huong dan, cong dong
cong san » cong tac
chan cau » phan cau, can cau, chinh cau

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 ((trong thi) OR (trong thoi)) nhung ((cong dan) or (cong san)) chan cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc thuyet tach - thanh ((trong thi) OR (trong thoi)) nhung ((cong dan) OR (cong san)) chan cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc thuyet tach - thanh ((trong thi) OR (trong thoi)) nhung ((cong dan) or (cong san)) chan cau".
• Adding a wildcard symbol may retrieve word variants: hoc thuyet tach - thanh ((trong thi) OR (trong thoi)) nhung ((cong dan) or (cong san)) chan cau*.