Perhaps you should try some spelling variations:
thanh trung » thanh tung
chiet tach » chieu sach
chieu sang » chieu sach, chieu xanh, hieu lang
cong thanh » dong thanh, cong trinh, truong thanh
trung va » truong va, trang va, trung ha
cong tan » cong tac, cong san, cong ty
toan cau » toan cao, toan ban, toan tap

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) or (chieu sang)) - thanh trung va nhung ((cong tan) OR (cong thanh)) toan cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((chiet tach) OR (chieu sang)) - thanh trung va nhung ((cong tan) OR (cong thanh)) toan cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((chiet tach) or (chieu sang)) - thanh trung va nhung ((cong tan) OR (cong thanh)) toan cau".
• Adding a wildcard symbol may retrieve word variants: hoc ((chiet tach) or (chieu sang)) - thanh trung va nhung ((cong tan) OR (cong thanh)) toan cau*.