Perhaps you should try some spelling variations:
thanh truong » thanh trung, thanh thuong, thanh tung
hieu sang » chieu sang, hieu quang, nhieu tang
hieu lang » chieu sang, hieu quang, nhieu tang
truong va » truong dai, truong cao, truong dao
bang cong » dang cong, bang song, hang cong
dan toan » van toan, manh toan, xuan toan
dan than » dan chan, ban than, van than
va bang » va nang, va lang, va ban

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

• Performing a fuzzy search may retrieve terms with similar spellings: doc ((hieu sang) OR (hieu lang)) - thanh truong va bang cong ((dan toan) or (dan than)) tap~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc ((hieu sang) OR (hieu lang)) - thanh truong va bang cong ((dan toan) OR (dan than)) tap.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc ((hieu sang) OR (hieu lang)) - thanh truong va bang cong ((dan toan) or (dan than)) tap".
• Adding a wildcard symbol may retrieve word variants: doc ((hieu sang) OR (hieu lang)) - thanh truong va bang cong ((dan toan) or (dan than)) tap*.