Perhaps you should try some spelling variations:
chieu xanh » chieu sach, chieu sang, chieu tinh
hieu manh » hieu nganh, dieu hanh, hien hanh
dung cong » dung trong
trung ap » trung cap, trung lap, trung dai
cong tac » cong ty
tac than » tac thanh, tam than, tac nhan
than cap » khan cap, thanh lap, thanh cac

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 ((chieu xanh) OR (hieu manh)) - hanh ((trung ap) OR (trung tam)) dung cong tac than cap~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc ((chieu xanh) or (hieu manh)) - hanh ((trung ap) OR (trung tam)) dung cong tac than cap~".
• Adding a wildcard symbol may retrieve word variants: doc ((chieu xanh) or (hieu manh)) - hanh ((trung ap) OR (trung tam)) dung cong tac than cap*.