Perhaps you should try some spelling variations:
chieu quan » thieu quang, hieu qua, che quan
hieu quan » hieu qua, lieu quan, thien quan
bang cong » dang cong, bang song, hang cong
hach toan » thanh toan, manh toan
anh tang » anh bang, anh dang, anh nang
tang cua » mang cua, hang cua, tang luan
cua bang » chua bang, cua ban, cua dang
tac toan » tap toan, tam toan, tich 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 quan) or (chieu quan)) - anh tang cua bang cong ((tac toan) OR (hach toan)) tap~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc ((hieu quan) OR (chieu quan)) - anh tang cua bang cong ((tac toan) OR (hach toan)) tap.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc ((hieu quan) or (chieu quan)) - anh tang cua bang cong ((tac toan) OR (hach toan)) tap".
• Adding a wildcard symbol may retrieve word variants: doc ((hieu quan) or (chieu quan)) - anh tang cua bang cong ((tac toan) OR (hach toan)) tap*.