Perhaps you should try some spelling variations:
tran thanh » ban thanh, van thanh, quan thanh
nhung cong » thong cong, hang cong, nhung don
hieu lang » chieu sang, hieu quang, nhieu tang
hanh tran » hanh trang, thanh tran, hanh tram
dung cong » dung trong
van tan » van tuan, van ban, van tai
tan tap » toan tap, han tap, tan tat

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: doi ((chinh sach) or (hieu lang)) - hanh tran thanh ((nhung cong) OR (dung cong)) van tan tap~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doi ((chinh sach) OR (hieu lang)) - hanh tran thanh ((nhung cong) OR (dung cong)) van tan tap.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doi ((chinh sach) or (hieu lang)) - hanh tran thanh ((nhung cong) OR (dung cong)) van tan tap".
• Adding a wildcard symbol may retrieve word variants: doi ((chinh sach) or (hieu lang)) - hanh tran thanh ((nhung cong) OR (dung cong)) van tan tap*.