Perhaps you should try some spelling variations:
hieu sang » chieu sang, hieu lang, hieu quang
canh manh » lanh manh, canh tranh, cach mang
hang cong » hang nong, bang cong, thanh cong
dang cong » dung cong
doc hieu » toc thieu, hoc thieu, hoc hien
manh cua » doanh cua, ban cua
khan cap » khan ap, khoan cam, phan cac
than cap » thanh lap, thanh cac, than cua

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 - canh manh cua ((hang cong) or (dang cong)) dan ((khan cap) or (than cap))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc hieu sang - canh manh cua ((hang cong) OR (dang cong)) dan ((khan cap) OR (than cap)).
• Adding a wildcard symbol may retrieve word variants: doc hieu sang - canh manh cua ((hang cong) or (dang cong)) dan ((khan cap) or (than cap))*.