Perhaps you should try some spelling variations:
hieu nganh » vien nganh, hiem ngan, hieu manh
chieu sang » chieu sach, chieu xanh, hieu lang
hanh khang » nhanh thang, thanh thang, van khang
khang su » khang cu, dang su, thong su
cong ban » cong bang, cong san, cong dan
cong tan » cong tac, cong san, cong thanh
than cao » toan cao, thai cao, than cap

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: ho ((hieu nganh) OR (chieu sang)) - hanh khang su dung ((cong ban) OR (cong tan)) than cao~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "ho ((hieu nganh) or (chieu sang)) - hanh khang su dung ((cong ban) OR (cong tan)) than cao~".
• Adding a wildcard symbol may retrieve word variants: ho ((hieu nganh) or (chieu sang)) - hanh khang su dung ((cong ban) OR (cong tan)) than cao*.