Perhaps you should try some spelling variations:
thanh trung » thanh tung
chieu sang » chieu sach, chieu xanh, nhieu tang
nhung cong » dung cong, thong cong, hang cong
hieu lang » hieu quang, nhieu tang, hieu van
trung cua » truong cua, trung tuan, trung cap
hang nong » thang long, han tong
dan van » dang van, doan van, dao 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 ((chieu sang) OR (hieu lang)) - thanh trung cua ((nhung cong) or (hang nong)) dan van ban~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((chieu sang) OR (hieu lang)) - thanh trung cua ((nhung cong) OR (hang nong)) dan van ban*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((chieu sang) OR (hieu lang)) - thanh trung cua ((nhung cong) or (hang nong)) dan van ban*".