Perhaps you should try some spelling variations:
hieu sang » chieu sang, hieu lang, hieu quang
luan hang » luan nang, luan han, luan hung
hang cong » dang cong, hang nong, bang cong
van thanh » ban thanh, van tuan
doc hieu » toc thieu, hoc thieu, hoc hien
anh dung » anh huong, sach dung, ung dung
anh dong » anh huong, anh son
dan than » dan chan, ban than, van than

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 - ((anh dung) OR (anh dong)) luan hang cong ((dan than) or (van thanh)) cao~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc hieu sang - ((anh dung) OR (anh dong)) luan hang cong ((dan than) OR (van thanh)) cao.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc hieu sang - ((anh dung) OR (anh dong)) luan hang cong ((dan than) or (van thanh)) cao".
• Adding a wildcard symbol may retrieve word variants: doc hieu sang - ((anh dung) OR (anh dong)) luan hang cong ((dan than) or (van thanh)) cao*.