Perhaps you should try some spelling variations:
hanh trang » thanh trung, hanh trinh, minh trang
hieu sang » chieu sang, hieu lang, hieu quang
dung cong » dung trong
doc hieu » toc thieu, hoc thieu, hoc hien
cua dung » cua dang, cua dong, qua dung
cong san » cong tac
than cao » toan cao, than cap, than sao
thai cao » tai cao, thoai cac, thuat cao

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

• If you are trying to use Boolean operators, they must be ALL CAPS: doc hieu sang - ((hanh trang) OR (canh tranh)) cua dung cong san ((than cao) OR (thai cao))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc hieu sang - ((hanh trang) or (canh tranh)) cua dung cong san ((than cao) OR (thai cao))~".
• Adding a wildcard symbol may retrieve word variants: doc hieu sang - ((hanh trang) or (canh tranh)) cua dung cong san ((than cao) OR (thai cao))*.