Perhaps you should try some spelling variations:
hieu sang » chieu sang, hieu quang, nhieu tang
hieu lang » chieu sang, hieu quang, nhieu tang
luan bang » luan nang, luan ban, luan tang
bang cong » dang cong, bang song, hang cong
anh dung » anh dong, anh huong, sach dung
tac toan » tap toan, hach toan, tich toan
tam toan » tap toan, tam than, pham toan

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