Perhaps you should try some spelling variations:
thanh nung » thanh tung, thanh hung, thanh dung
hieu lang » chieu sang, hieu quang, nhieu tang
dang cong » dung cong
doi hieu » doi chieu, doc hieu, doi hien
nung cao » nang cao, nhung cau, quang cao
cong van » cong vang, cong san, song van
ban hanh » ban hang
ban cau » bang cau, ban can, van cau

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: doi hieu lang - thanh nung cao dang cong van ((ban cau) OR (ban hanh))~.
• Adding a wildcard symbol may retrieve word variants: doi hieu lang - thanh nung cao dang cong van ((ban cau) or (ban hanh))*.