Perhaps you should try some spelling variations:
thanh trung » thanh tung
chieu sach » chinh sach, chiet tach, chieu sang
hieu lang » chieu sang, hieu quang, nhieu tang
trung cua » truong cua, trung tuan, trung cap
cua nhung » va nhung
cong vang » cong lang, cong quang, cong ngang
cong van » cong san, song van, cong tan
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 ((hieu lang) or (chieu sach)) - thanh trung cua nhung ((cong van) OR (cong vang)) toan cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((hieu lang) OR (chieu sach)) - thanh trung cua nhung ((cong van) OR (cong vang)) toan cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((hieu lang) or (chieu sach)) - thanh trung cua nhung ((cong van) OR (cong vang)) toan cau".
• Adding a wildcard symbol may retrieve word variants: hoc ((hieu lang) or (chieu sach)) - thanh trung cua nhung ((cong van) OR (cong vang)) toan cau*.