Perhaps you should try some spelling variations:
nhung duong » nhung dung, nhung huong, nhung tuong
duong minh » duong manh, truong minh, thong minh
doc hieu » toc thieu, hoc thieu, hoc hien
hieu luc » hieu luat, hieu qua
tranh va » tranh van, trang va, trinh va
toan cao » toan tap
toan ban » van ban
canh » anh, can, hanh

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 luc - canh tranh va nhung duong minh ((toan cao) OR (toan ban))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc hieu luc - canh tranh va nhung duong minh ((toan cao) OR (toan ban))".
• Adding a wildcard symbol may retrieve word variants: doc hieu luc - canh tranh va nhung duong minh ((toan cao) OR (toan ban))*.