Perhaps you should try some spelling variations:
thanh trung » thanh tung
hieu quang » thieu quang, hieu quan, hieu qua
khong cong » thong cong, khong cang, chong cong
hieu lang » chieu sang, nhieu tang, hieu van
cua khong » hua khong, cua phuong, cua thuong
van thanh » ban thanh, van tuan
thanh cau » thanh chau, thanh mau, nhanh cau
cong van » cong vang, cong san, song van

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 (hieu quang)) - ((thanh trung) or (canh tranh)) cua khong cong van thanh cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((hieu lang) OR (hieu quang)) - ((thanh trung) OR (canh tranh)) cua khong cong van thanh cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((hieu lang) OR (hieu quang)) - ((thanh trung) or (canh tranh)) cua khong cong van thanh cau".
• Adding a wildcard symbol may retrieve word variants: hoc ((hieu lang) OR (hieu quang)) - ((thanh trung) or (canh tranh)) cua khong cong van thanh cau*.