Perhaps you should try some spelling variations:
hieu sang » chieu sang, hieu lang, hieu quang
dung cong » dung trong
cong bang » cuong bang, dong bang, hong bang
doc hieu » toc thieu, hoc thieu, hoc hien
cap dung » ap dung, cao dung, chan dung
than cap » thanh lap, thanh cac, than cua
khan cap » khan ap, khoan cam, phan cac

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: doc hieu sang - ((thanh tung) or (thanh cong)) cap dung cong bang ((than cap) or (khan cap))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc hieu sang - ((thanh tung) OR (thanh cong)) cap dung cong bang ((than cap) OR (khan cap)).
• Adding a wildcard symbol may retrieve word variants: doc hieu sang - ((thanh tung) or (thanh cong)) cap dung cong bang ((than cap) or (khan cap))*.