Perhaps you should try some spelling variations:
hieu sang » chieu sang, hieu lang, hieu quang
cua duong » cua dong, cua huong, qua duong
doc hieu » toc thieu, hoc thieu, hoc hien
hanh ban » thanh ban, hanh san, hanh han
hang ban » hang luan, hang va, hang tai
cong dan » cong tan, huong dan, cong dong
cong san » cong tac

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 ban) OR (hang ban)) cua duong ((cong dan) OR (cong san)) van ban~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc hieu sang - ((hanh ban) or (hang ban)) cua duong ((cong dan) OR (cong san)) van ban~".
• Adding a wildcard symbol may retrieve word variants: doc hieu sang - ((hanh ban) or (hang ban)) cua duong ((cong dan) OR (cong san)) van ban*.