Perhaps you should try some spelling variations:
doanh hoan » doanh doanh, doanh khoa, doanh nhan
hieu lang » chieu sang, hieu quang, nhieu tang
hoan gian » khoan giao, dan gian, don gian
gian lang » gian dan
hoc hieu » hoc thieu, hoc hien, doc hieu
cong dan » cong san, cong tan, cong dong
than man » than ma, thanh san, tran manh

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: hoc hieu lang - doanh hoan gian lang ((cong dan) OR (huong dan)) than man~.
• Adding a wildcard symbol may retrieve word variants: hoc hieu lang - doanh hoan gian lang ((cong dan) or (huong dan)) than man*.