Perhaps you should try some spelling variations:
hieu tinh » chieu tinh, lieu tinh, kieu tinh
dung cong » dung trong
hang cong » dang cong, hang nong, bang cong
doc hieu » toc thieu, hoc thieu, hoc hien
tranh va » tranh van, trang va, trinh va
dan toan » van toan, dan than, manh toan
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 tinh - canh tranh va ((dung cong) or (hang cong)) dan toan cao~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc hieu tinh - canh tranh va ((dung cong) OR (hang cong)) dan toan cao.
• Adding a wildcard symbol may retrieve word variants: doc hieu tinh - canh tranh va ((dung cong) or (hang cong)) dan toan cao*.