Perhaps you should try some spelling variations:
hieu lang » chieu sang, hieu quang, nhieu tang
hanh tinh » hanh trinh, nhanh tinh, thanh tinh
chat dang » chan dang, chat quang, cao dang
dang cong » dung cong
son thanh » ban thanh, van thanh
doc hieu » toc thieu, hoc thieu, hoc hien
ban hanh » ban hang

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 lang - hanh tinh chat dang cong ((son thanh) OR (ban hanh)) chau~.
• Adding a wildcard symbol may retrieve word variants: doc hieu lang - hanh tinh chat dang cong ((son thanh) or (ban hanh)) chau*.