Perhaps you should try some spelling variations:
huong quan » luong quan, cuong quan, vuong quan
quan trong » gian trong
hieu lang » chieu sang, hieu quang, nhieu tang
doc hieu » toc thieu, hoc thieu, hoc hien
cong tan » cong tac, cong thanh, cong ty
cong san » cong tac
toan cau » toan ban, toan tap, toan tai
toan cao » toan ban, toan tap

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 lang - anh huong quan trong ((cong tan) OR (cong san)) ((toan cau) or (toan cao))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc hieu lang - anh huong quan trong ((cong tan) OR (cong san)) ((toan cau) OR (toan cao)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc hieu lang - anh huong quan trong ((cong tan) OR (cong san)) ((toan cau) or (toan cao))".
• Adding a wildcard symbol may retrieve word variants: doc hieu lang - anh huong quan trong ((cong tan) OR (cong san)) ((toan cau) or (toan cao))*.