Perhaps you should try some spelling variations:
thanh trung » thanh tung
chiet tach » chieu sach
hoc chiet » hoc thiet, hoc nhiet, hoc hien
trung va » truong va, trang va, trung ha
cong sat » cong suat, cong hat, cong nhat
cong san » cong tac
phan dau » phan tu
hang dau » hang va, hang tai

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc chiet tach - thanh trung va nhung ((cong sat) OR (cong san)) ((phan dau) or (hang dau))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc chiet tach - thanh trung va nhung ((cong sat) OR (cong san)) ((phan dau) OR (hang dau)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc chiet tach - thanh trung va nhung ((cong sat) OR (cong san)) ((phan dau) or (hang dau))".
• Adding a wildcard symbol may retrieve word variants: hoc chiet tach - thanh trung va nhung ((cong sat) OR (cong san)) ((phan dau) or (hang dau))*.