Perhaps you should try some spelling variations:
canh trang » canh tranh, hanh trang, banh trang
hieu lang » chieu sang, hieu quang, nhieu tang
dang cong » dung cong
doc hieu » toc thieu, hoc thieu, hoc hien
trang va » tran van, hang va
cong ban » cong bang, cong san, cong tan
than cap » khan cap, thanh lap, thanh cac
toan ban » van ban
va dang » van dang, va nang, va lang

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 - canh trang va dang cong ban ((than cap) or (toan ban))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc hieu lang - canh trang va dang cong ban ((than cap) OR (toan ban)).
• Adding a wildcard symbol may retrieve word variants: doc hieu lang - canh trang va dang cong ban ((than cap) or (toan ban))*.