Perhaps you should try some spelling variations:
thanh trung » thanh tung
trung quang » truong quang, trong quang, trung quan
hieu quang » thieu quang, hieu quan, hieu qua
chieu sach » chinh sach, chiet tach, chieu sang
ban than » ban thanh, van thanh, ban hang
than cau » toan cau, phan cau, than cap

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc ((hieu quang) or (chieu sach)) - thanh trung quang ((dung cong) OR (dung trong)) ban than cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((hieu quang) OR (chieu sach)) - thanh trung quang ((dung cong) OR (dung trong)) ban than cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((hieu quang) or (chieu sach)) - thanh trung quang ((dung cong) OR (dung trong)) ban than cau".
• Adding a wildcard symbol may retrieve word variants: hoc ((hieu quang) or (chieu sach)) - thanh trung quang ((dung cong) OR (dung trong)) ban than cau*.